irunBEN'GURIONUNIVERSITY

OF THE NEGEV

SIXTHISRAEL MATERIALS ENGINEERING

CONFERENCEIMEC VI

PROGRAM AND ABSTRACTS

THE DEAD SEA, ISRAELFEBRUARY 24-25 1993

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BENGUHIONUNIVERSITY

OF THE NEGEV

SIXTHISRAEL MATERIALS ENGINEERING

CONFERENCEIMEC VI

PROGRAM AND ABSTRACTS

THE DEAD SEA, ISRAELFEBRUARY 24-25 1993

TABLE OF CONTENTS Page #

Organizing Committee

Conference Sponsors

Scientific Program

Authors Index

Abstracts

'-Plenary Sessions

"-Technical Sessions

•-Posters

I

1 - 18

19 - 22

A-l - C-2

1.1.1 - 4.4.5

PI.3 - P2.53

ORGANIZING COMMITTEE

D. Eliezer, Ben Gurion University of the Negev (Chairman)D. Itzhak, Ben Gurion University of the NegevE. Abramov, Nuclear Research Center, NegevM. Fass, Israel Defence ForceA. Grinbaum, Bromine Compounds Ltd.J. Haddad, Ben Gurion University of the NegevN. Nir, Armament Development AuthorityH. Rahman, Technion, Israel Institute of TechnologyA. Siegman, Technion, Israel Institute of TechnologyM. Talianker, Ben Gurion University of the NegevM. Wolf, National Council for Research and DevelopmentY. Zchavi, Technion, Israel Institute of Technology

CONFERENCE SPONSORS;

* Ben Gurion University of the Negev

* Technion, Israel Institute of Technology

* Israel Atomic Energy Commission

* Armament Development Authority

* Ministry of Science and Technology

* Ministry of Energy

* Carmel Bank

* Landseas (Israel) Ltd.

* Buehler UK, Ltd.

CONFERENCE ORGANIZERSORTRA LTD.2 Kaufman StreetP.O. Box 50432Tel Aviv 61500, IsraelTel: 972-3-664825, Fax: 972-3-660952

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SCIENTIFIC PROGRAM

W E D N E S D A Y . FEBRUARY 24. 1993

10:00-10:30OPENING SESSIONChairmen:D. Ellezer, Ben Gurion UniversityA. Siegman, Technion

Green Hall

OPENING REMARKSD. EUezer, Chairman, Organizing CommitteeA. Braverman, President, Ben Gurion University of the Negev

10:30-11:20PLENARYChairmen:D. Eliezer,A. Siegman,

SESSION A

Ben GurionTechnion

University

Green Hall

A-l STRUCTURAL MATERIALS FOR NASPT.M.F. Ronald, Wright-Patterson Air Force Base, USA

A-2 MICROSTRUCTURE, PHASE TRANSFORMATIONS AND MECHANICALPROPERTIES OF ORDERED ORTHORHOMBIC Ti NbAl-BASED ALLOYSR.G. Rowe, GE Corporate Research and Development, USA

11:20-11:40 C o f f e e B r e a k Foyer

11:40-12:45PLENARY SESSION BChairmen:D. Itzhak, Ben Gurion UniversityI. Gefen, Ministry of Defense

Green Hall

B-l POLAR LANGMUIR BLODGET FILMS FOR NONLINEAR OPTICSAND PYROELECTRIC DEVICES •J.B. Lando, CWR

B-2 SYNTHESIS AND PROPERTIES OF TRI-ALUMINIDES BY MECHANICALALLOYING •R.B. Schwarz, Los Alamos National Lab., USA

B-3 ATOMISTIC SIMULATION OF HYDROGEN-INDUCED FRACTURE OF ANIRON-BASED SUPERALLOYN.R. Moody, S.M. FoUes, J.E. Angelo, M.I. Baskes,Sandia National Laboratories, USA

* Abstract not submitted

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12:45-13:15POSTER SESSION PI Sufat Hamidhar

Pl.l DEVELOPMENT OF COMPOSITE COATINGS BY PLASMA SPRAY *M. Konrad, Ben Gurion University, G. Gurevitz, Israel Aircraft Industries

PI.2 PROCESS OF STABLE AUSTENITE PRODUCTION DURING THE POINTWELDING OF MARAGING STEELS •A. Pasternak, Y. Neiman, T. Wagner, Israel Military Industries

PI .3 PROPERTIES OF CEMENTED CARBIDE WITH DIFFERENT CoCONTENT ANDDIFFERENT GRAINS SIZE OF TUNGSTEN CARBIDE FOR CONSTANT MEANFREE PATHR. Porat, I. Gavisb, Iscar

P1.4 ASSESSMENT OF FATIGUE LIFE OF ALUMINUM ALLOY COMPONENTS WITHCRACKS USING RANDOM LOAD MONITORING SYSTEMR. Arone, S. Ustilovsky, G. Sharshukov, A. Loksb, L. Potepun, Technion

P1.5 SOURCES OF ACOUSTIC EMISSION IN AL-LI BASE ALLOYS AND THEIRVARIATIONS WITH HEAT TREATMENTV. Zeides, I. Roman, The Hebrew University

PI .6 SELF-STRENGTHENING OF THE STAINLESS-STEEL UNDER SHOCK LOADINGE. Zaretsky, Ben Gurion University of the Nsgev

P1.7 DISLOCATION SOURCES IN SHOCK DEFORMATION OF METALSE. Zaretsky, Ben Gurion University of the Negev

P1.8 LOCAL REINFORCEMENT OF METAL CASTINGS WITH CERAMIC FIBRES/PARTICLESB. Barkai, N. Kami, Technion

P1.9 FORMATION OF Co AND Ta SILICIDES ON Si (100) and Si (111)SUBSTRATES FROM CODEPOSITED Co AND Ta FILMSS. Darwish, J. Pelleg, Ben Gurion University of the Negev

P1.10 PROBABILISTIC PROCESSES AND FORMING STRUCTURE DURINGSOLIDIFICATIOND. Kopeliovicu, Antek, Ltd.

Pl.H THERMAL TREATMENT AND BRAZING IN VACUUM AND HIGH VACUUMFURNACES •I. Goldfarb, Chromat Ltd.

P1.12 INFLUENCE OF GRAIN BOUNDARY SEGREGATION ON THE THERMOPHYSICALPROPERTIES OF CERAMICST. Gambaryan, E.Y. LUovsky, M. Shapiro, Technion

P1.13 TEMPERATURE AND GAS PRESSURE DEPENDENCES OF THERMALCONDUCTIVITY OF DENSE AND INSULATING CERAMIC MATERIALSE. Y. Litovsky, M. Shapiro, Technion

* Abstract nut submitted

IW E D N E S D A Y . F E B R U A R Y 2 4 . 1 9 9 3 /Cont inued

POSTER SESSION Pi/Continued

P1.14 SYNTHESIS OF IRON, NICKEL AND COBALT TITANIDES FROM FINEELEMENTAL POWDERSE. Paransky, I. Gotmao, E.Y. GutmaDUS, Technion

P1.15 DEVELOPMENT AND CHARACTERIZATIONS OF COMPOSITE SOLID ELECTROLYTEFOR BIPOLAR LITHIUM BATTERIES FOR ELECTRIC VEHICLESE. Peled, D. Golodnitsky, Tel Aviv University

P1.16 CAPACITORS WITH GRAIN BOUNDARY BARRIER LAYER MICROSTRUCTUREIN THE BaO-(SrO)-TiO AND BaO-SnO -TiO SYSTEMSV. Stancovski, M. Kravcnik, A. Goldstein, A. Bar, Technion

P1.17 EFFECT OF HEAT TREATMENT CONDITIONS IN ALUMINUM-MATRIXCOMPOSITESC. Alexandra, P. Moldovan, Polytechnic Institute Bucharest,G.V. Ghica, INTEC, Romania

P1.18 IN SITU QUALITY MONITORING TECHNIQUE FOR A HIP PROCESSO. Tevet, Ben Gurion University, O. Yeheskel, U. Atzmony,M.P. Dariel, NRC

P1.19 MICROSTRUCTURAL EVALUATION OF CAST ALUMINUM ALLOY MATRIXCOMPOSITESP. Moldovan, C. Alexandra, Polytechnic Institute Bucharest,G.V. Ghica, INTEC, Romania

P1.20 UNUSUAL MECHANICAL PROPERTIES OF HIGH-STRENGTH ROLLED STEELWITH MACROANISOTROPIC STRUCTUREP.D. Odessky, S.I. Morozov, M.R. Uritsky, A.B. Steblov, V.T. Cheraenko,TsNIISK, Russia

P1.21 MAGNETOCHEMISTRY OF THE TETRAHALOFERRATE (III) IONS IN THEA3Fe2X9 SERIESR. Suaviv, IMI, R.L. Carlin, The University of Illinois, USA

P1.22 STRUCTURE AND PROPERTIES OF RAPIDLY SOLIDIFIED GOLD-TITANIUMALLOYST. Abuud, D. Shechtman, Technion

P1.23 MICROSTRUCTURAL AND COMPOSITIONAL CHARACTERIZATION OF TiW/Al-0.8%SI/TiW/PtSi/(100)SiA. Ashkenazi, Y. Komem, Technion I. Lerner, National Semiconductor

P1.24 UTILIZING ACOUSTIC-EMISSION AS A NON-DESTRUCTIVE METHOD FORPRESSURE VESSELSA. Mittelman, The Hebrew University

P1.25 Au-Cu-Cd ELECTROPLATED ALLOYS STRUCTURE AND MECHANICAL PROPERTIESS. LJbov, E. Igner, Jotaly Ltd.

P1.26 PROCESSING OF A HIGH-PURITY ALUMINA MATERIALO. Glozman, L. Baum, W.D. Kaplan, D.G. Brandon, Technion

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Poster Session Pi/Continued

P1.27 THERMOMECHANICALLY STRENGTHENED SHAPES FOR BUILDING STRUCTURESMADE OF LOW-CARBON AND LOW-ALLOYED STEELA. Klyucli, Technion

P1.28 PERFORMANCES AND WEAR PHENOMENA OF THE TiN-COATED TWIST DRILLSD. Julean, L. Kerekes, M. Carean, Technical Unveristy of Cluj, Romania

P1.29 SOLID STATE AMORPHIZATION OF Cu-Ti-B POWDER SYSTEM BYMECHANICAL ALLOYINGM. Savransky, S. Berger, BX. Weiss, Technion

P1.30 STUDY OF CHEMICAL VAPOR INFILTRATION PROCESS FOR SiC MATRIXCOMPOSITESN. Nawi, D. Itzhak, U. Admon, M.S. Dariel, NRCN, Ben Gurion University ofthe Negev

P1.31 HIGH TEMPERTURE PERICLASE INSULATION1. Yaniv, R. Cytermann, T. Litovsky, IMI

PI .32 INTERNAL RESIDUAL STRESSES AND WEAR RESISTANCE PROPERTIES OFCOMPOSITE NiCr ELECTROCHEMICAL DEPOSITSS. Eskin, O. Berkh, J. Zabavi, J. Lanfir, L, Zevin, Technion

P3.33 QUANTITATIVE NON-DESTRUCTIVE LAYER-BY-LAYER ANALYSIS OF THESURFACE SUB-REGION OF SOLIDS BY EPMAA. Berner, Technion

P1.34 EDS AND X-RAY DIFFRACTION STUDY OF TERNARY ARTIFICIALSUPERLATTICESI. Goldfarb, E. Zolotoyabko, A. Berner, D. Shechtman, Technion

Pl.3.5 PREADHESION LASER SURFACE TREATMENT OF COMPOSITE POLYMER,POLYMERS AND METALS ADHERENDSM. Hotel, J. Zahavi, Technion, A, Bucbman, H. Doduik, Rafael

PI .36 LASER PLANARIZATIONS. Tamir, J. Zahavi, Technion, Y. Lerner, National Semiconductor

P1.37 DURABILITY OF GLASS FIBRE REINFORCED CEMENT1TIOUS COMPOSITESWITH DIFFERENT LOW ALKALI/LOW LIME MATRICESA. Bentur, K. Kovler, Technion,I. Odler, Technical University Clausthal, Germany

P1.38 CORROSION AND STRESS CORROSION CRACKING BEHAVIOR OF AIS1 304AND AISI 316 STAINLESS STEELS IN 55% LiBrO. Elias, I. Lev, D. Itzhak, Ben Gurion University of the NegevP. Peled, Bromine Compounds Ltd.

P1.39 THE INFLUENCE OF ELECTRON IRRADIATION ON ADHESION OF METAL FILMS• S. Stolyarova, Eltam Technology Inc.

P1.40 THE EFFECT OF FREQUENCY IN PLASMA MATERIALS PROCESSINGA. Raveb, NRC, A. Bettelbeim, J.E. Klemberjj-Sapieha, L. Martinu,M.R. Wertheimer, Ecole Polytechnique, Montreal, Canada

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W E D N E S D A Y . F E B R U A R Y 2 4 . 1 9 9 3 /Continued

Poster Session Pi/ContinuedP1.41 THE POSSIBLE USE OF MIXED IONIC ELECTRONIC CONDUCTORS, INSTEAD

OF ELECTROLYTES, IN FUEL CELLSI. Riess, Technion

P1.42 FRACTURE OF CARBON FIBRE REINFORCED PEEK UNDER STATIC ANDFATIGUE CONDITIONS: THE INFLUENCE OF THE DEGREE OF CRYSTALLINITYA. Tregub, H. Hare), G. Marom, The Hebrew UniversityC. Migliaresi, University of Trento, Italy

P1.43 RAPID THERMAL ANNEALING OF HIGH DOSE ARSENIC-IMPLANED SILICONE.N. Shauly, National Semiconductor, Technion, ¥. Komem, Technion

P1.44 CHARACTERIZATION OF THE IMPLANT ENERGY DISTRIBUTION OF HIGHCURRENT BF2 IMPLANTS INTO (001) SiN. Bacharach, Technion, E.N. Shauly, National Semiconductor, Technion,Y. Komem, Technion, Y. Avrahamov, National Seminconductor

P1.45 A COMPARISON OF TCA (TRICHLOROATHANE) AND DCE (TRANS 1,2DICHLOROETHLENE) - GROWN OXIDES ON SILICONE.N. Shauly, National Semiconductor, Technion, R. Mor, Y. Avrahamov,Technion

PJ.46 INVESTIGATION OF THE ACOUSTIC FIELD GENERATED BY REACTIVESPUTTERED ZnO LAYERS IN ACOUSTO-OPTIC DEVICES, BY MEANS OFX-RAY DIFFRACTIONE. Jacobsohn, E. Zolotoyabko, D. Shechtman, Technion

P1.47 IN SITU X-RAY DIFFRACTION DURING THE FORMATION OF TiSi2 C49FROM Ti-Si MULTILAYER ON Si(lOO)J. Sariel, Nuclear Research Center, H. Chen, University of Illinois, USA

P1.48 PREDICTION AND CALCULATION OF THE PROPERTIES OF CERAMICS WITHSPINAL STRUCTUREE.N. Men, I. Sinitsky, D.G. Brandon, Technion

P1.49 THE SYNERGISTIC EFFECT OF ENVIRONMENTAL PARAMETERS ON THEBEHAVIOR OF PLASTIC MATERIALR. Huberman, E. Gutman, D. Itzhak, Ben Gurion University of the Negev

P1.50 THE EFFECTS OF DOPANTS ON THE DEVELOPMENT OF THE MICROSTRUCTUREIN THIN FILMS OF Al OW.D. Kaplan, D.G. Brandon, Technion

P1.51 MICROSTRUCTURAL EVALUATION OF ALIGNED CERAMIC MATRIX COMPOSITESN. Shafry, D.G. Brandon, Technion

P1.52 A COMPUTER PROGRAM FOR THE CALCULATION OF ATOMIC POSITIONSON GENERAL GRAIN BOUNDARIESW.D. Kaplan, D.G. Brandon, Technion

P1.53 STRONG ELECTROSORPTION AT THE THIN BISMUTH FILM/ELECTROLYTEINTERFACEA. Bluvstein, Advanced Technologies Center

P1.54 EVOLUTION OF EQUILIBRIUM THIN CRACK CAUSED BY DIFFUSION INHIGH STRENGTH MATERIAL AND CERAMICS »V. Strelcov, Israel

13:15-14:20 L u n c h B r e a k

* Abstract not submitted- 5 -

W E D N E S D A Y . F E B R U A R Y 2 4 . 1 9 9 3 / C o n t i n u e d

14:30-16:00SESSION 1.1 - POLYMERSChairmen:E. Gutman, Ben Gurion UniversityA. Cohen, Rafael

Kesem Hall

1.1.1 POLYMERIC ANTIPLASTICIZATION POLYCARBONATE WITHPOLYCARPROLACTONEM. Sinister, M. Narkis, A. Siegman, Technion

1.1.2 DIELECTRIC AND DYNAMIC MECHANICAL CURE MONITORING OFPOLYESTER RESIN: MOLECULAR INTERPRETATIOND. Alpersteio, A. Siegman, M. Narkis, Technion

1.1.3 THERMOELASTICITY OF FIBER/MATRIX INTERFACIAL INTER-ACTION IN POLYMER COMPOSITE MATERIALSA. Tregub, G. Marom, Hebrew University V.P. Privalko, Academy of Scienceof Ukraine, H.G. Kilian, University of Ulm, Germany

1.1.4 DEGRADATION OF POLYMERS BY HYPERTHERMAL ATOMIC OXYGENR. Vered, G. Nahor, G.D. Lempert, NRCN G. Marom, Hebrew University,L. Lifsbitz, NRC

14:30-16:00SESSION 1.2 - COMPOSITE MATERIALS IChairmen:Z. Berger, LAIO. Yeheskel, NRCN

Jerusalem Hall

1.2.1 TRANSCRUSTALLINITY IN THERMOPLASTIC COMPOSITES AND ITSINFLUENCE ON THEIR MECHANICAL PERFORMANCEN. Klein, G. Marom, Hebrew University of Jerusalem

1.2.2 POLYETHYLENE FIBRES - POLYETHYLENE MATRIX COMPOSITES:PREPARATION AND PHYSICAL PROPERTIESA. Teishev, Hebrew University of Jerusalem, S. lncardona, TheUniversity of Trento, Italy, G. Marom, Hebrew University of Jerusalem

1.2.3 STRUCTURE CHARACTERIZATION OF LASER PROCESSED WC/Co LAYERSM. Boas, Rafael, M. Bamberger, Technion

1.2.4 MICROSTRUCTURE AND MECHANICAL PROPERTIES OF SiC PLATELET /CORDIERITE GLASS-CERAMIC COMPOSITESR. Chaim, Technion

1.2.5 SURFACE ENGINEERING OF STEELS IN MOLTEN BORAXS. B. Fazluddio, A. Koursaris, University of Wilwalersrand,

.C. Ringas, MATTEK, SCIR, K. Cowie Melal Technology Engineering,South Africa

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W E D N E S D A Y . F E B R U A R Y 2 4 . 1 9 9 3 / c o n t i n u e d

14:30-16:00SESSION 1.3 - MATERIAL PROCESSING 1Chairmen:G. Cohen, NRCNA. Levin, Technion

Green Hall

1.3.1 ELECTRICAL RESISTIVITY OF 3104 Al-ALLOYSA. Stern, NRCN, L. Phillips, A.H. Cahn National Institute of Standardsand Technology, USA

1.3.2 DEPOSITION OF DIAMOND FILMS ON CEMENTED CARBIDES (WC + Co)A.K. Mehlmann, A. Fajer, S.F. Dirnfeld, Y. Avigal, TechnionR. Porath, Iscar Ltd.

1.3.3 SOLID STATE SYNTHESIS OF CoAl AND NiAl INTERMETALLICS VIAHIGH PRESSURE CONSOLIDATION OF FINE ELEMENTAL POWDERSL. Farber, E.Y. Gutmanas, Technion

1.3.4 THERMODYNAMIC CONSIDERATION FOR SOLID STATE AMORPHIZATIONBY MECHANICAL ALLOYINGY. Chakks, S. Berger, B.Z. Weiss, Technion

1.3.5 FACTORS AFFECTING THE QUALITY OF ELECTRON BEAM (EB) WELDSOF Al 1050 END CAPS TO Al 6061 TUBESA. Stern, NRCN and Ben Gurion Univeristy of the Negev,I. Dahan, NRCN, D. Eliezer, Ben Gurion University of the Negev

14:30-16:00SESSION 1.4Chairmen:M. Dariel, NRCND. Fuks, Ben Gurion University

THIN FILMS I Disco

1.4.1 HOMOGENIZATION OF LAYERED THIN FILMS UNDER ELECTRIC CURRENTL. Klinger, A. Katsman, A. Levin, Technion

1.4.2 MAGNETRON-SPUTTERED Co-DEPOSITED THIN FILMS AS A METHOD FORCONSTRUCTION OF MULTI-COMPONENT PHASE SYSTEMSI. Goldfarb, D. Shechtman, Technion

1.4.3 ELASTIC INTERACTION BETWEEN PRECIPITATES IN THIN LAYERSR. Shneck, M.P. Dariel, Ben Gurion University of the Negev,A. Brofcman, Jerusalem

1.4.4 GRAIN GROWTH IN COPPER-CHROMIUM MULTILAYERSU. Admon, NRCN, M.P. Dariel, NRCN, Ben Gurion Univeristy,G. Kimmel, J. Sariel, NRCN, A. Stecnman, NRCN, Ben Gurion University,

> L. Zevin, Ben Gurion University

1.4.5 ELECTROMIGRATION IN THIN FILMS: TIME DEPENDENCE OF STRESSDISTRIBUTION AND HILLOCK GROWTHA. Katsman, L. Klinger, A. Levin, E. Glickman, Tcchnion

16:00-16:20 C o f f e e B r e a k Foyer

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W E D N E S D A Y . F E B R U A R Y 2 4 . 1 9 9 3 / c o n t i n u e d

16:20-17:50SESSION 2.1 - CERAMICSChairmen:R. Chaim, TechnionE. Manor, Ben Gurion University

Jerusalem Hall

2.1.1 CERAMIX MATRIX COMPOSITES PRODUCED BY DIRECT MELT OXIDATIONE. Manor*, Ben Gurion University of the Negev,H. Ni, C.G. Levi, University of California, Santa Barbara, USAR. Mebrabian, Carnegie Mellon University, USA

2.1.2 TENSILE BEHAVIOR OF ALUMINA CARBON/EPOXY LAMINATED SYSTEMD. Sherman, F A Lecki, University of California, Santa Barbara, USA

2.1.3 PROCESSING OF Al O -SiC POWDER "NANOCOMPOSITES"I. Levin, D.G. Brandon, Technion

2.1.4 GLASS-CERAMICS: OPTIMIZATION OF STRUCTURE, PROPERTIES ANDTECHNOLOGYR. Khodakovskaya, IMI

ENVIRONMENTAL16:20-17:50SESSION 2.2EFFECT IChairmen:Y. Yahalom, TechnionM. Talianker, Ben Gurion University

Green Hall

2.2.1 MICROSTRUCTURAL AUDITING TO TRACEABLE STANDARDS IN THE PCDRIVEN QUALITY CONTROL LABORATORYB. Bousfield, Buehler Europe Ltd., UK

2.2.2 THE EFFECT OF TRAPPING AND RELEASE PROCESS ON THERMONUCLEARFUSION REACTORS PERFORMANCEE. Abramov, Ben Gurion University of the Negev, NRCN

2.2.3 INTERFACIAL EFFECTS IN THE PRESENCE OF HYDROGEN INAl/Al3Ti/SiC

G. Solovioff, D. Eliezer, Ben Gurion University of the Negev

2.2.4 A NEW MATHEMATICAL APPROACH BASED ON THE CIRCULAR DIAPHRAGMTO EXPLAIN THE BLISTER EFFECT ON IMPLANTED METALSD. Moreno, E. Abramov, NCRN, D. Eliezer, Ben Gurion University ofthe Negev

2.2.5 HYDROGEN EFFECT IN INTERMETALLIC TITANIUM-ALUMINIDES ALLOYSJ. Haddad, D. Eliezer, Ben Gurion University of the Negev

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JW E D N E S D A Y . F E B R U A R Y 2 4 . 1 9 9 3 / C o n t i n u e d

16:20-17:50SESSION 2.3 - COATINGS IChairmen:A. Kaufman, IKA Industrial Consult.Z. Livne, NRCN

Kesem Hall

2.3.1 EXTREMELY SMALL CRYSTALS IN MULTILAYERED C.V.D. COATINGOF TiC + TiN AND THEIR EFFECT ON THE PERFORMANCE OFCUTriNG TOOLSR. Porat, N. Arisbkevich, A, Geltz, Iscar Ltd.

2.3.2 ELECTROCHEMICAL DEPOSITION OF ALLOYS OF GRADUATECOMPOSITION Fe/CuR. Interto', Y. Yahalom, Technion

2.3.3 THE INFLUENCE OF A THIRD ELEMENT ON THE INTERFACE REACTIONSIN METAL MATRIX COMPOSITES (MMC): Al-GRAPHITE SYSTEMD. Lotker, J. Pelleg, D. Fuks, Ben Gurion University of the Negev,M. Ganor, O. Yeheskel, NRCN

2.3.4 DIAMOND-LIKE CARBON FILMS: PREPARATION, MICROSTRUCTURE-PROPERTY RELATIONSHIPA. Raveh, NRCN, L. Martinu, J.E. Klemberg-Sapieha, MR. Wertheimer,Ecole Polytechnique, Montreal, Canada

16:20-17:50SESSION 2.4 - ELECTRONIC MATERIALSChairmen:J. Pelleg, Ben Gurion UniversityN. Croitoru, Tel Aviv University

Disco

2.4.1 ELECTRONIC PACKING AND THERMAL DESIGN *C. Colin, AT&T Bell Laboratories, USA

2.4.2 PATTERNING OF SUPERCONDUCTING YBCO FILMSM. Riabkina-Fisbman, J. Zahavi, Technion

2.4.3 AMORPHOUS DIAMOND-LIKE-CARBON FOR MIS AND MIM DIODESM. Alaluf, D. Aizenman, N. Croitoru, Tel Aviv University

2.4.4 BARIUM NONATITANATE DIELECTRC MINIATURE RESONATORSFOR MICROWAVE CIRCUITSA. Goldstein, M. Kravchik, V. Stancovsky, V. Belov, Technion

2.4.5 CORRELATION BETWEEN ELECTRICAL PROPERTIES AND STRUCTURALCHANGES IN Sb IMPLANTED S^ Ge LAYERSZ. Atzmon, M. Eizenberg, Technion, *}.W? Mayer, Y. Shachara-Diamand,Cornell University, USA, F. Schaffler, Daimler-Benz AG, Germany

* Abstract not submitted

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T H U R S D A Y . F E B R U A R Y 2 5 . 1 9 9 3

09:00-10:10PLENARY SESSION CChairmen:S. Dirafeld, TechnionA. Stem, NRCN

Green Hall

C-l OXIDATION BEHAVIOUR OF INTERMETA1LIC PHASES FOR HIGHTEMPERATURE APPLICATIONHJ. Grabke, M. Steihorst, M.W. Bnimm, Max Planck Institute,Dusscldorf, Germany

C-2 ELECTROMAGNETIC MONITORING OF METAL PROCESSINGA.H. Kahn, L.C. Phillips, National Institute of Standards and Technology,USA, A. Stern, NRCN

C-3 MECHANICAL ALLOYING AS A PROCESSING ROUTE FOR Ni-Al BASEDINTERMETALLICS *M. Dollar, Institute of Technology, Illinois, USA

10:10-10:30 C o f f e e B r e a k

10:30-11:15POSTER SESSION P2

Foyer

Sufat Hamidbar

P2.1 A METHOD FOR THE MEASUREMENT OF THE THERMAL CONDUCTIVITYTENSOR IN THIN LAYERS OF YBa2Cu O ?

L. Kornblit, N. Gluzman, M. Auslander, Ben Gurion University of the Negev

P2.2 STRUCTURE OF TiN NITROGEN RICH FILMSR.R. Manory, RMIT, Australia, G. KimmeL NRC

P2.3 BEHAVIOR OF ALUMINUM BRASS •P. Yoffe, Y. Barucb, Israel Electric Corp., S. Libov, Technion

P2.4 XRD INVESTIGATION OF CHROMIUM ALLOYED MEDIUM CARBON STEELX-20 CrMoV12.1M. Velin, P. Yoffe, Israel Electric Corp., S. Libov, Technion

P2.5 HYDROGEN CONDITION IN MIDDLE CARBON LOW ALLOY BAINITE STEEL:LOCALIZATION, DIFFUSION AND FLAKES GENERATION IN LARGEFORGINGP. Yoffe, Israel Electric Corp.

P2.6 STEEL AND IRON CAST RESISTANT AGAINST WEAR: OPTIMIZATION OFRESISTANCE IN WEAR *I. Gilad, IAI

P2.7 A NEW METHOD FOR DETERMINATION OF HEAT TRANSFER COEFFICIENTSIN THE PROCESS OF RAPID QUENCHING OF AMORPHOUS METALLICRIBBONSV. Manov, M. Geller, E. Broyk-Levinson, TechnionA. Manucbin, Urals Polylechnical Institute, Russia

'Abstract not submitted

T H U R S D A Y . F E B R U A R Y 2 5 . 1 9 9 3 /Continued

Poster Sess ion P2/Continued

P2.8 PECULIARITIES OF GLASS-FORMING CONDITIONS OF INORGANIC,CHALCOGENIDIC AND METALLIC GLASSESV. Manov, D. Shechtman, Technion

P2.9 HYDROGEN ATTACK ON COPPER AND COPPER-BERYLLIUM ALLOY SURFACED, Moreno, NRC, D. Eliezer, Ben Gurion University of the Negev

P2.10 DECAGONAL QUASICRYSTALLINE PHASE IN THE Al-Cu-Co ALLOY SYSTEMB. Gmshko, R. Wittmann, K. Urban, Forschungszentrum Julich GmbH, Germany

P2.ll SPRAY PROCESSING OF METAL MATRIX COMPOSITESEJ. Lavernia, University of California, USA

P2.12 SOME PRINCIPLES OF CREATION OF PROTECTION STRUCTURESL.I. Slepyan, Tel Aviv University

P2.13 IRRADIATION EFFECT ON THE PROPERTIES OF Cu-0.8% Cr ALLOY:POSSIBILITY OF THE SLIGHTLY DOPED Cu-ALLOYS USE AS CANDIDATEMATERIAL FOR THERMONUCLEAR REACTOR DIVERTER PLATESV.M. Ustinovshchikov, INFODISK Temed Ltd.L.N. Bystrov, N.R. Bochvar, Academy of Science, Russia

P2.14 CYCLIC IRRADIATION EFFECT ON CREEP BEHAVIOR OF Fe-BASE BCCALLOYS, MODEL ALLOYSL.N. Bystrov, A.B. Tsepelev, Academy of Science, RussiaV.M. Ustinovshchikov, INFODISK Temed Ltd.

P2.15 REPLICATION MICROSCOPY AND A REMNANT LIFE ASSESSMENT TECHNIQUEB. Feldraan, Y. Man, A. Kaufman, IKA Industrial Consulting

P2.16 INFLUENCE OF THE FORM OF STRESS-STRAIN DIAGRAM ON THESHOCK RESISTANCE OF MATERIAL AND STRUCTURESL, Slepyan, Tel Aviv University, M. Ayxenberg-Stepanenko, Negev AdvancedTechnical Center

P2.17 ENVIRONMENTAL EFFECTS ON THE BEHAVIOR OF CARBON/EPOXY COMPOSITEY. Bainer, A. Grinberg, LAI,E. Gutman, Ben Gurion University of the Negev

P2.18 ON THE STRUCTURE PERFECTION OF YTTRIUM ALUMINUM GARNET REALCRYSTALSY. Rosenberg, I. Keldman, Tel Aviv University

P2.19 EFFECT OF SHORT TIME EXPOSURE TO HIGH TEMPERATURE ON THETENSILE STRENGTH OF AA 2024 - T8 ALUMINUM SHEETSS. Bar Ziv, A. Cohen, A. Ledelsky, Rafael

P2.20 ADVANCED GRAPHITE FIBRES *D. Ronen, IMI

P2.21 CORROSION OF COMMERCIALLY PURE ALUMINUM TYPE A5 1050 DURINGLONG SERVICE AT IRR2 REACTORB. Herrmann, A. Munitz, Y. Gurevitz, C. Cotter, NRCN

'Abstract not submitted

- 1 1 -

T H U R S D A Y . F E B R U A R Y 2 5 . 1 9 9 3 / C o n t i n u e d

Poster Session P2/Continued

P2.22 TENSILE PROPERTIES OF NEUTRON IRRADIATED CO WORKED ALUMINUM6063 ALLOYA. Munitz, F. Simca, A. Stecbmao, C. Cotler, M. Talyunker, Ben GurionUniversity of the Negev, S. Oahan, NRCN

P2.23 M1CROSTRUCTURE OF TIG AND ELECTRON BEAM COPPER-STAINLESSSTEEL WELDSA. Munitz, C. Cotler, H. Sacham, E. Aberman, NRCN

P2.24 GROWTH OF A METASTABLE EUTECTIC IN Al-U ALLOYS SOLIDIFIEDIN A COPPER MOLDA. Munitz, C. Cotler, E. Nechama, NRCN,M. Talyanker, Ben Gurion University of the Negev

P2.25 SULFUR SEGREGATION ON NICKEL SURFACESO. Segel, M. Polak, Ben Gurion University of the Negev

P2.26 POTENTIAL-CURRENT OSCILLATIONS OF TITANIUM ALLOY EXPOSEDTO IN NaBR SOLUTION UNDER APPLIED POTENTIAL CONDITIONSY. Shterenberg, D. Itznak, Ben Gurion University of the Negev

P2.27 MODEL FOR PHASE FORMATION IN THIN-FILM METAL/SEMICONDUCTORSYSTEMS FROM AN AMORPHOUS INTERLAYERM. Beregovsky, M. Eizenberg, Technion

P2.28 ANISOTROPY IN RESIDUAL STRAINS AND LATTICE PARAMETER OFREACTIVE SPUTTER-DEPOSITED Zr FILMSA. Laor, L. Zevin, J. Pelleg, Ben Gurion University of the Negev

P2.29 BLISTERS FORMATION DUE TO HELIUM IMPLANTATION OF COPPER ANDITS ALLOYS *D. Moreno, NRCN, E. Abramov, O. Eliezer, Ben Gurion Universityof the Negev

P2.30 HYDROGEN INTERACTION WITH NICKEL PRE-IMPLANTED WITH He:THE EFFECT OF THE DOSE AND POST-IMPLANTATION ANNEALINGE. Abramov, NRCN, Ben Gurion University, G. Solovioff, Ben GurionUniversity of the Negev, Y. Grinberg, NRCN, G.D. Lampert, Soreq NuclearCenter, D. Eliezer, Ben Gurion University of the Negev

P2.31 PRELIMINARY STUDY ON MICROSTRUCTURE OF Al-Be ALLOYS *M. Brill, O. Shmariau, A. AdJer, S. Harush, NRCE. Abramov, NRC, Ben Gurion University of the Negev

P2.32 STRESS CRACKING AS A RESULT OF HYDRIDE FORMATION IN U-0.1% CrS. Zalkind, R. Ashcenazy, S. Harusb, A. Venkert, D. Moreno, D. Halperin,NRCN, E. Abramov, NRCN, Ben Gurion University of the Negev

P2.33 CVD AND MBE OF RAREFIED H2 OF SiGe SOLID SOLUTIONK. Ljutovich, Uzbek Academy of Science, Uzbekistan

P2.34 TEXTURE OF URANIUM ALLOYS DUE TO PLASTIC DEFORMATION *A. Dabush, D. Dayan, G. Kimmel, Y. Dahan, M. Dariel, NRCN

*Abstract not submitted

- 1 2 -

T H U R S D A Y . F E B R U A R Y 25 1 9 9 3 /Continued

Poster Session P2/Continued

P2.35 THE INFLUENCE OF METALLIC GETER ON THE OXYGEN IMPURITY INAs-Se INFRARED FIBER •E. Nir, I. Tugendhaft, A. Bornsteln, Soreq Nuclear Research Center,N. Croitoni, Tel Aviv University

P2.36 THE BEHAVIOR OF METALS UNDER INDUCED POTENTIALD. Itzhak, Ben Gurion University of the Negev,H. Straze, Bromide Compounds Ltd.

P2.37 HYDROGEN INDUCED BLISTERS FORMATION AND GROWTH IN NICKEL PRE-IMPLANTED WITH HELIUMG. Solovioff, Ben Gurion University of the Negev, E. Abramov, NRCND. Eliezer, Ben Gurion University of the Negev

P2.38 THE CORROSION BEHAVIOR OF TITANIUM-ALUMINIDE ALLOYSA. Ben-Gigi, G. Solovioff, D. Eliezer, Ben Gurion University of the Negev

P2.39 HYDROGEN EFFECTS IN Al-A^Ti-SiCG. Solovioff, E. Abramov, D. Eliezer, Bin Gurion University of theNegev, EJ. Lavernia, University of California, USA

P2.40 THE CORROSION BEHAVIOR OF Al/Al3Ti/SiCN. Wertsman, G. Solovioff, D. Eliezer Ben Gurion University of the Negev,EJ. Laveroia, University of California, USA

P2.41 HYDROGEN EFFECT ON THE ORDERED ORTHORHOMBIC Ti NbAl BASED ALLOYSN. Stern, G. Solovioff, D. Eliezer, Ben Gurion University of the Negev

P2.42 PHASE FORMATION BETWEEN CO-DEPOSITED Co-Ta THIN FILM AND SINGLECRYSTAL SILICON SUBSTRATEG. Briskin, J. Pelleg, M. Talyanker, Ben Gurion University of the Negev

P2.43 THE SOURCE OF FRINGE CONTRAST OBSERVED IN THE INTERFACE BETWEENHELIUM BUBBLE AND CuBe ALLOY MATRIXD. Moreno, NRCN, D. Eliezer, Ben Gurion University of the Negev

P2.44 FCGR AND FRACTURE TOUGHNESS IN Ti6Al-4V OF DIFFERENT MORPHOLOGIESJ. Brandelstein, Rafael, L. Levin, Technion

P2.45 THE EFFECT OF MACHINING PARAMETERS ON THE SURFACE ROUGHNESSOF Ni COATED Al MIRRORSG. Kohn, Ben Gurion University of the Negev, Y. Shneor, RotemIndustries, R. Papiar, IAI

P2.46 A NEW SELECTIVELY ABSORBING COATINGT. Werber, J. Yahalom, Technion

P2.47 CONTROLLED THERMOPROTECTIVE COATINGS FOR GAS TURBINESE. Shvarzshtein, T. Werber, J. Yahalom, Technion

P2.48 THEORETICAL METHOD FOR CALCULATION OF THE DIFFUSION DEPTHC. Samoila, University of Transylvania of Brasov, Romania

'Abstract not submitted

- 1 3 -

\

IT H U R S D A Y . F E B R U A R Y 2 5 . 1 9 9 3 / C o n t i n u e d

Poster Session P2/Contlnued

P2.49 METHODS FOR OBTAINING METALLIC MAGNESIUM FOR MODIFICATIONOF NODULAR CAST IRONA. Crisan, I. Ciobanu, University of Transylvania of Brasov, Romania

P2.50 HYDRIDES FORMATION IN a2 AND T T I T A N I U MM. Dangur, J. Haddad, D. Eliezer. Ben Gurion University of the Negev

P2.51 Ge SINGLE CRYSTAL FILMS GROWN BY MBE ON (Ca,Sr)F/AL O ANDGaAs SUBSTRATESE. Redmard, E. Grunbaum, G. Oeufsher, Tel Aviv University

P2.52 WIDE ANGLE XRD STUDY OF THE EFFECT OF PROCESSING CONDITIONS ONPOLY (P-PHENYLENE BENZOBISTHIAZOLE)E.L. Garstein, Y. Cohen, Technion

P2.53 OXIDATION GROWTH IN 1NTERMETALLIC Ti-25-10-3-1M. Dangur, D. Eliezer, Ben Gurion University of the Negev

11:15-12:45SESSION 3.1 - ENVIRONMENTAL EFFECTS IIChairmen:E. Abramov, NRCNM. Volf, Israel

Green Hall

3.1.1 SIMULATION OF HYDROGEN ISOTOPES DIFFUSION THROUGH METALLATTICE CONTAINS CONTINUOUS ENERGY TRAPSE. Abramov, NRCN, Ben Gurion University of the Negev,N. Yakobovitcb, Israel Air Force, E. Berman, D. Eliezer, Ben GurionUniversity of the Negev

3.1.2 SURFACE MECHANOCHEMISTRY OF CRYSTALLINE SOLIDSE. Gutman, Ben Gurion University of the Negev

3.1.3 NON1SOTHERMAL EFFECTS DURING THE MAIN CRACK PROPAGATION INBRITTLE MATERIALSE. Druinsky, L. Levin, R. Arone, A. Klyuch, Technion

3.1.4 THE EFFECT OF TIN AND NICKEL ADDITION ON THE ENVIRONMENTALBEHAVIOUR OF SINTERED DUPLEX STAINLESS STEELA. Sharon, D. Itzhak, Ben Burion University of the Negev

- 1 4 -

T H U R S D A Y . F E B R U A R Y 2 5 . 1 9 9 3 / C o n t i n u e d

t11:15-12:45SESSION 3.2 - PHYSICAL METALLURGYChairmen:P. Moldovan, Poiytecnic Inst. RomaniaR. Shurck, Ben Gurion University

Kesem HaU

3.2.1 X-RAY DIFFRACTOMETRY IN MATERIALS SCIENCEL. Zevin, Ben Gurion University of the Negev

3.2.2 STUDY IN IMPROVEMENT OF WEAR BEHAVIOUR IN HIGH KINEMATICPAIRS BY WAY OF A COMPUTER PROGRAME. Bennan, S. I. Grunfeld, Ben Gurion University of the Negev

3.2.3 ASPECTS OF BEHAVIOUR CONCRETE MACHINE TOOL STRUCTURES USINGFINITE ELEMENT METHODC. Ispas, C. Dogariu, A. Craciunescu, Polytechnic Institute of Bucharest,Romania

3.2.4 A MODEL DESCRIBING THE CURVED ARRHENIUS PLOTS IN SELF -DIFFUSION OF METALSV. Segel, J. Pelleg, D. Fuks, Ben Gurion University of the Negev,S. Dorfman, Technion

11:15-12:45SESSION 3.3 - CORROSIONChairmen:J. Zahavi, TechnionP. Pelted, Bromine Compounds Ltd.

Jerusalem Hall

3.3.1 THE INFLUENCE OF SURFACE TREATMENTS OF ALUMINUM ALLOYS ONTHEIR RESISTANCE TO CORROSION FATIGUEM. Landkof, J. Rezek, A.Cohen, Rafael

3.3.2 FORMICARY CORROSION OF COPPERI. Weisshaus, A. Kaufman, E. Erdan, Orlil Ltd.

3.33 STRESS CORROSION CRACKING OF STAINLESS STEEL IN BROMIDEHEAVY BRINESP. Peled, Bromine Compounds Ltd., D. Itzhak, Ben Gurion University ofthe Negev

3.3.4 THE EFFECT OF MELT TEMPERTURE ON THE ELECTRICAL RESISTIVITYAND CRYSTALLIZATION TEMPERATURE OF Al -La-Ni AND Al -Ce.-NiAMORPHOUS ALLOYS 91 5 4 91 .s 4V. Manov, D. Shechtman, Technion, A. Rubshtefn, A. Voronel, Tel AvivUniversity

3.3.5 USE OF ELECTRICAL EQUIVALENT CIRCUIT TO SIMULATE SOME CASESOF PROTECTIVE COATINGS UNDER CORROSION CONDITIONSJ. Hazan, J. Yahalom, Technion

-15 -

T H U R S D A Y . F E B R U A R Y 2 5 . 1 9 9 3 / C o n t i n u e d

11:15-12:45SESSIONChairmen.R. Porat,M. Pass,

3.4 -

IscarORT,

COATINGS II

Ltd.Israel

Disco

3.4.1 SURFACE DIFFUSION AND COATING OF SiC AND B C BY INTERACTIONWITH METAL POWDERSP. Mogiltvsky, I. Gotman, E.Y. Gutmamts, Technion,WA. Kaysser, Max Planck Institute, Stuttgart, Germany

3.4.2 ELECTROPHORETIC DEPOSITION OF HYDROXYAPATICE COATINGS FORMEDICAL APPLICATIONSA. Zhitomirsfcy, L. Gal-Or, Technion

3.4.3 M1CROSTRUCTURE, PHASE COMPOSITION AND RESIDUAL STRESSES INPLASMA SPRAYED THERMAL BARRIER COATINGSM. Levit, S. Berger, BZ. Weiss, Technion

3.4.4 PRODUCTION OF Cr BASED COMPOSITE COATINGS IN THE PRESENCEOF ADDITIVESO. Berth, S. Eskln, J. Zahavi, Technion

3.4.5 DIAMOND COATINGSZ. Klein, A. Markovitch, A. Shalmon, Rafael

12:45-14:00 L u n c h B r e a k Dinine Room

14:00-15:30SESSION 4.1 - MECHANICALBEHAVIOUR OF MATERIALSChairmen:N. Nir, RafaelJ. Haddad, Ben Gurion University

Jerusalem Hall

4.1.1 MECHANOCHEMICAL METHODS IN MATERIAL SCIENCEPJ. Butyagin, Russian Academy of Science, Russia

4.1.2 RESIDUAL MECHANICAL PROPERTIES OF ABLATIVE COMPOSITESON EXPOSURE TO HIGH TEMPERATURESH. Weisshaus, I. Engelberg. ADA

4.1.3 STRESS AND FAILURE ANALYSIS OF TAPERED ADHESIVE JOINTSA. Buchmao, F. Weinstein, Y. Holdengraber, I. Honigman, H. Dodiuk, Rafael

4.1.4 FATIGUE MECHANISMS OF 95/5 Pb/Sn MICRO SOLDER JOINTS UNDERFULLY REVERSED SHEARN. Nir, AT&T Bell Laboratories, USA, A.R. Storm, T.D. Dudderar, Rafael

4.1.5 FRACTURE TOUGHNESS MEASUREMENTS FOR CERAMIC MATERIALA. Ashur, A. Cohen, Rafael

T H U R S D A Y . F E B R U A R Y 2 5 . 1 9 9 3 /Con t i nued

14:00-15:30SESSION 4.2 -Chairmen:L. Zevin, BenC. Samoila,

COMPOSITE MATERIALS II

GurionUniv

Universityof Transylvania

Kesem Hall

4.2.1 THE EFFECT OF IMPURITIES ON THE TENSILE ELONGATION OFBERYLLIUM0 . Yeheskel, NRCN

4.2.2 THE PREPARATION OF FIBER REINFORCED ALUMINUM SiCT/6061BY DIFFUSION BONDINGM. Paz, J. Mironi, N. Atzmon, M. Elkaiyam, Israel

4.2.3 COMPARATIVE STUDIES CONCERNING THE BEHAVIOUR OF RESIN/FIBREGLASS COMPOSITE MATERIALS1. Constantly Polytechnic Institute of Bucharest, G. Dan, S.C Simtex,Romania

4.2.4 RECRYSTALLIZATION OF TUNGSTEN BASE HEAVY METAL ALLOYSC. Weinberger, D. Chaiat, TAAS Israel Industries Ltd.

4.2.5 LASER SURFACE ALLOYING OF FERROUS ALLOYS WITH CrB :SOLIDIFICATION BEHAVIOUR AND MICRO-STRUCTUREG. Shafirstein, M. Bamberger, Technion, S. Aricly, F. Maisenhalder,M. Langohr, DLR Stuttgart, Germany

14:00-15:30SESSION 4.3 - MATERIAL PROCESSING IIChairmen:I. Ciobanu, Univ. of TransylvaniaS. Moisa, Ben Gurion University

Green Hall

4.3.1 ULTRASONICS AS A RESEARCH TOOL IN POWDER TECHNOLOGYO. Yeheskel, H. Klimker, Y. Gefen, M. Ganor, NRCN

4.3.2 EFFECT OF PROCESSING ON MICROSTRUCTURE AND PROPERTIES OFTUNGSTEN HEAVY ALLOYSE.Y. Gutman, D. Zack, D. Chaiat, Technion

4.3.3 STRUCTURAL CHARACTERIZATION OF EPITAXIAL THIN FILMS BYRECIPROCAL SPACE MAPPINGG.H.O. Daalderop, T.R. Ryan, Philips Analytical X-Ray, The Netherlands

4.3.4 MICROSTRUCTURE OF Al-U ALLOYS SOLIDIFIED AT COOLING RATESBETWEEN 0.03-0.5 K/SECA. Munitz, V.Y. Zenou, C. Cotier, A. Zahavi, Z. Barkai, NRCN

4.3.5 IMPROVING PRODUCT DESIGN THROUGH A CONTROLLED EXPERIMENTB. Milman, 1. Sirota, TAAS Israel Industries, D.M. Steinberg, Tel AvivUniversity

- 1 7 -

T H U R S D A Y . F E B R U A R Y 2 5 . 1 9 9 3 /Continued

THIN FILMS II14:00-15:30SESSION 4.4Chairmen:M. Polak, Ben Gurion UniversityD. Borochov, Israel

4.4.1 COMPUTERIZED SYSTEM FOR EVALUATION OF ENERGY ABSORPTIONDURING LASER TREATMENT OF METALSM. Geller, E. Armon, M. Bamberger, Technion

4.4.2 THE INTERFACE FORMED BETWEEN PbBiSrCaCuO HIGH-T SUPER-CONDUCTOR CERAMIC AND Ag OR Ag-BASED ALLOYSN. Froumin, J. Baram, M. Polak, Ben Gurion University of the Negev

4.4.3 DEPOSITION OF DIAMOND-LIKE CARBON FILMS BY LASER PLASMATECHNIQUEJ. Karpmao, M. Riabkina-Fishman, J. Zahavi, Technion

4.4.4 RECONSTRUCTION OF SURFACE AND ENVIRONMENTAL SENSITIVEMECHANICAL BEHAVIOR OF METALSEX. Glickman, The Hebrew University of Jerusalem

4.4.5 THE NEW METHOD OF CRYSTAL PERFECTION CHARACTERIZATIONUSING X-RAY BRAGG REFLECTIONSY. Rosenberg, Tel Aviv University

15:30-15:45 C o f f e e B r e a k Foyer

15:45-16:15CLOSINGChairman:D. Itzhak,

SESSION

Ben Gurion University

Green Hall

-18-

A U T H O R S ' I N D E X

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A.U.D.M.C.D.

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-39-

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- 20 -

A. ManuchinE. ManorR.R. ManoryV. ManovA. MarkovitchL. Martinu6. Marom

L. MartinuJ.W. MayerA.K. MehlmannR. MehrabianE.H. MenC. MigliaresiB. MilmanJ. MlroniA. MittelmanP. MogilevskyF. MoldovanN.R. Moody,R. MorD. Moreno

S.I. Morozov,A. Munitz

6. NahorM. NarkisN. Nawi,E. NechamaY. Neiman,H. NiE. NirN. MirP.D. Odessky,I. OdlerR. PapiarE. Paransky,A. Pasternak,M. PazE. Peled,P. PeledJ. Pelleg

M. PolakL.C. PhillipsR. PoratL. PotepunV.P. PrivalkoA. RavebE. RadmardJ. Rezek

P2.72.1.1P2.23.3.4, P2.7, P2.83.4.5PI. 401.1.3, 1.1.4, 1.2.1,1.2.2, PI.422.3.42.4.51.3.22.1.1PI. 48PI.424.3.54.2.2PI. 243.4.1PI.17, PI.19B-3PI.45P2.9, P2.29, 2.2.4,P2.32, P2.43PI. 204.3.4, P2.21, P2.22,P2.23, P2.241.1.41.1.1, 1.1.2PI. 30P2.24PI.22.1.1P2.354.1.4PI. 20PI. 37P2.45PI. 14PI. 24.2.2PI. 153.3.3, PI.382.3.3, 3.2.4, PI.9P2.28, P2.424.4.2, P2.25C-2, 1.3.1PI.3, 1.3.2, 2.3.1PI. 41.1.32.3.4, PI.40P2.513.3.1

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- 2 2 -

ABSTRACTS

1

I

PLENARY SESSIONS

I

\STRUCTURAL MATERIALS FOR NASP

Terence M.F. Ronald

NASP Joint Program Office

Wright-Patterson Air Force Base

Ohio 45433, USA

The materials classes of primary interest for the NASP X-30 experimental vehicle include

titanium alloys, titanium-based metal-matrix composites, carbon-carbon composites, ceramic

matrix composites. On the airframe, these materials would be used as lightweight skin

panels of honeycomb-core, Iruss-core, or integrally stiffened thin sheet configuration.

Where necessary, they would be cooled with the gaseous hydrogen fuel by incorporating

coolant passage into the structure. In the engines, they would be used in the hot gas

path of the ramjet/scramjet, and also in the inlet and nozzle areas. The engine

application represents a particularly challenging problem because of the severe

environment, involving high thermal, acoustic and mechanical loading. In this case, the

structural components almost certainly will be actively cooled, meaning that the materials

may be in contact with hot hydrogen from the fuel, in addition to hot oxygen and the

gaseous products of combustion.

I

A - l

MICROSTRUCTURE, PHASE TRANSFORMATIONS AND MECHANICAL

PROPERTIES OF ORDERED ORTHORHOMBIC Ti2NbAl-BASED ALLOYS

R.G. Rowe

GE Corporate Research and Development,

Schnectady, NY 12309, USA

Titanium aluminide alloy and process development for the past decade has centered upon

balancing elevated temperature strength and creep resistance with room temperature

fracture toughness and ductility. Ordered orthorhombic Ti2NbAl-based alloys lie upon a

new higher strength vs. fracture toughness curve than conventional titanium aluminides.

This has made them attractive candidates for elevated temperature aircraft and aerospace

applications in both monolithic and composite form. The tensile and creep properties of

these alloys will be described as a function of microstructure and quaternary alloy

additions. Their transformation behavior, and equilibrium phase relations, which are less

well established than for conventional titanium aluminides, will be reviewed. Changes in

grain boundary structure have been observed during long time creep exposure for grain

boundaries under normal applied stress. The relationship of these changes to the

transformation behaviour of the alloys will be discussed.

A-2

I ATOMISTIC SIMULATION OF HYDROGEN-INDUCED FRACTURE OF AN IRON-

| BASED SUPERALLOY

N.R. Moody, S.M. Foiles, J.E. Angelo, and M.I. Baskes

Sandia National Laboratories, Livermore, CA 94551-0969

Austenitic supetalloys are often used in hydrogen and hydrogen-producing environments

due to their good resistance to hydrogen effects compared with other alloy systems.

Nevertheless, these alloys can exhibit dramatic reductions in ductility and crack growth

resistance when exposed to high hydrogen fugacity environments. We studied the effects

of high fugacity hydrogen in the crack growth susceptibility of one of these superalloys,

IN903. This work showed that the resistance to crack growth decreased by a factor of

three when exposure to hydrogen triggered a change in fracture mode from microvoid

coalescence to intergranular failure. Although the grain boundaries are known trap sites

for hydrogen, the effects of hydrogen on the intergranular fracture process are not well-

defined, being attributed to a either a decrease in atomic bond strength or to the

enhancement of localized plasticity. Neither of these mechanisms are verifiable through

direct observation in bulk samples using currently available techniques. As a

consequence, we combined Monte Carlo and molecular dynamics calculations with the

embedded atom method (EAM) to help to define the effects of hydrogen trapping on the

fracture of grain boundaries through simulation. For all lattices, fracture began by the

breaking of bonds next to the polyhedral defects that characterize the boundary structure

followed by rapid failure of the remaining bonds across the boundary plane. These

simulations showed that hydrogen did not alter the sequence of events comprising the

fracture process but did lower the fracture stress from 18 GPa to a lower limiting value of

8 GPa as the trap sites along the boundary plane filled. The hydrogen atoms in these sites

were the only hydrogen atoms involved in the fracture process. Within the constraints

imposed in these calculations, the results of this study showed that the "inherent" effect of

hydrogen is to reduce the cohesive force between atoms across the boundary. This

presentation will discuss these results and their impact on our understanding of how

hydrogen affects fracture in iron and nickel-rich superalloys.

This work supported by U.S. DOE Contract DE-AC04-76DP00789 and the Office of

Basic Energy Sciences, Division of Materials Science.

H - J

I OXIDATION BEHAVIOUR OF INTERMETALLIC PHASES FOR HIGH

I TEMPERATURE APPLICATION

1 H.J. Grabke, M. Steihorst and M.W. Brumm

j Max-Planck-Institut fur Eisenforschung, Diisseldorf, Germany

The oxidation behaviour of NiAl, NbAl3 and different alloys from the system Ni-Nb-Al

was investigated in the temperature range 700-1400°C.

NiAl proves to be rather oxidation resistant, at high temperatures > 100°C protective

AI2O3 scales are formed. But, the oxidation, especially of NiAl with Ni excess, leads to

cavity formation beneath the scale and spalling of the scale. Between 800-1000°C at first

metastable AI2O3 - modifications are formed which gradually transform to a - AI2O3, this

transformation is accelerated for NiAl-Cr alloys. Local attack of NiAl under internal

oxidation and outgrowth of Ni/A^O^ protrusions was observed under special conditions,

low p<>2 and intermediate temperatures.

Under corresponding conditions NbAl3 shows "pesting", i.e. disintegration into fine

oxidized particles. This phenomenon is initiated by oxygen diffusion into grain

boundaries and AI2O3 precipitation at the grain boundaries, as shown by Auger electron

spectroscopy. But also at high temperatures > lOOO'C NbAl3 is not oxidation resistant,

since upon cracking of the AI2O3 scale the Nb2Al formed below the scale is oxidized

under formation of fast growing oxides - a stratified scale of A2IO3 and of AlNbC>4 and

layers is obtained.

In contrast to the single phase materials some multiphase alloys behave much better,

concerning as well the oxidation at intermediate temperatures (no pesting) as the high

temperature oxidation, e.g. NiAl-Cr, NiAl-NbNiAl and NiAl-NbNiAl-NbAl3.

c- i

ELECTROMAGNETIC MONITORING OF METAL PROCESSING

Arnold H. Kahn*. Louis C. Phillips* and Adin Stern**

*National Institute of Standards and Technology, Gaithersburg, MD 20899, U.S.A.

I ' **Israel Atomic Energy Commission, Nuclear research Center-Negev,f Beer Sheva 84190, Israel

Electromagnetic methods provide excellent means of non-contact sensing of properties of

metals during processing. In the applications to be described, eddy currents are induced

in the material under test by a primary exciting coil, which applies an ac magnetic field to

the material. A secondary coil, the pickup, responds to the field as modified by the

currents induced in the test material. The response depends upon the electrical

conductivity and magnetic permeability of the material, its defects and inhomogeneities,

and on its geometric shape and dimensions. Greatest information is obtained by

sweeping the frequency of excitation, so as to probe varying depths of the material. In

the cases to be discussed we shall be concerned with simple uniform shapes such as

uniform sheets and cylindrical rods.

In the application to the measurement of the temperature of aluminum sheets we utilize the

temperature dependence of the electrical resistivity of the material. The electrical

resistivity of a dilute alloy of aluminum is that of pure aluminum plus additive

contributions associated with alloying composition, the degree of solid solution of the

components, and the metallurgical state. In cases of controlled conditions with varied

composition we have been able to perform on-line eddy current monitoring of the

temperature of moving aluminum sheet, in the range of 300° to 400°C, to an accuracy of

+ 16°C. For the range of compositions used there would have been an apparent spread of

60°C. Fluctuations in the temperature of the moving sheet limited the precision; with

improved control the accuracy demonstrated would have been higher. Further testing is

' in progress.

Four additional applications will be discussed briefly. 1.) In the hot isostatic pressing and

consolidation of metal powders, eddy current methods have been used to monitor the

dimensions of a cylindrical canister containing the powders and thereby to obtain as in

situ measurements of density during the processing. 2.) An application to the

measurements of the resistivity of carbon-carbon sheet during heat treatment has been

accomplished using a through transmission technique similar to that used for aluminum,

but at higher frequencies. 3.) The method is also being applied to the determination of

the depth of case hardening of steel shafts. Here magnetic and electrical changes due to

case hardening are detected. 4.) An application to measuring the velocity of liquid metal

flow in now under way in at NIST.

C -2

r

TECHNICAL SESSIONS

IfI

IPOLYMERIC ANTDPLAOTICIZATION POLYCARBONATE WITH

POLYCAPROLACTONE

M. Shuster*, M. Narkis*, A. Siegmann**

•Department of Chemical Engineering

••Department of Materials Engineering

Technion-Israel Institute of Technology, Haifa 32000, Israel

Physical blends of polycarbonate (PC) with polycaprolactone (PCL), containing 0-30%

PCL were prepared by melt mixing. The compatible blends were studied using

differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), mechanical

testing, rheological and density measurements. Yield strength, elastic modulus and

density of the blends were found to attain maximum values, depending on PCL content,

while Tg continuously decreased. PCL presence resulted in the embrittlement of PC as

detected by impact and tensile tests. Simultaneously, the PC's P-transition intensity was

depressed, as detected by DMA. Activation energy of PC secondary relaxation process

was found to be somewhat higher for PC/PCL blends than for PC. Thus, local,

intermolecularly non-cooperative motions, usually associated with ^-relaxation, are

restricted in the presence of PCL. The addition of PCL to PC results in increased shear

sensitivity and lower high shear rates viscosity; improving processability.

i . i . i

DIELECTRIC & DYNAMIC MECHANICAL CURE MONITORING OF POLYESTER

RESIN: MOLECULAR INTERPRETATION *

D. Alperstein, A. Siegman, M. Narkis

Technion-Israel Institute of Technology, Haifa 32000, Israel

Dielectric measurements as a mean to monitor polymeric resins during cure has gained

much interest. This is due to the accuracy of this method, especially in light of the recent

technological breakthroughs in producing accurate, easy to use sensors. In spite of its

increasing popularity only a few basic phenomenological principles are currently

understood concerning the dielectric relaxation during cure. Moreover, molecular insight

to the dielectric relaxations is rare due to the vast complexity of dealing in molecular terms

with a constantly changing polymer. f<

In order to partially overcome few of these obstacles unsaturated polyester was chosen as a ;

model system for its relative chemical simplicity.

In this system the curing process involves only crosslinking with no chemical changes of

the ester groups. Hence, the dielectric relaxation should reflect molecular rearrangements

only due to network formation. In order to elaborate the frequency range, two additional

dynamic methods were used: (1) Compressive dynamic mechanical method simultaneously

with the dielectric measurements, (2) Dynamic rheometry. :

The results show a frequency influence on the molecular motion causing the relaxation. In

the dielectric and mechanical measurements very fast molecular vibration modes can be

followed. Such fast modes take place short time after the gel-point. At this stage of the

curing process the polymer network is still loose, having a low crosslinking density. This

loose network, swollen with most of the styrene monomer (the gel-point is at about 6%

conversion), enables these fast molecular vibration modes. The rheological results show,

however, relaxation at very high conversion which corresponds to slow vibration modes in

a highly crosslinked network. The general origin of all molecular motions during cure is «•

demonstrated by applying the same power law to all relaxation times, from the resin to the

highly crosslinked network. •'

i . i . ?

fTHERMOELASTICITY OF FIBER / MATRIX INTERFACIAL INTERACTION IN POLYMER

COMPOSITE MATERIALS

A. Tregub*, G. Marom*, V.P. Privalko**, H.G. Kilian***

*Casali Institute of Appl. Chemistiy, Graduate School of Appl. Science and Technology,} } The Hebrew University of Jerusalem, Jerusalem 91904, Israeli **Institute of Macromolecular Chemistry, Academy of Science of Ukraine,

48 Kharkov Shaussee, Kiev, 252160, Ukraine***Abt. Exp. Physik, University of Ulm, Oberer, Eselsberg, Ulm D7900, Germany

It is well known, that structure and properties of the fibre/matrix interface have a pronouncedeffect on the mechanical performance and physical properties of composite materials [1].Different methods for characterizaton of the fiber/matrix interface exist, including pull-out,microdebonding, fragmentation (critical length) and fibre push-out (indentation) tests. [2]. Suchmethods do not provide a thermodynamic description of the microfailure process, and,particularly, they do not enable to determine the onset of microfailure more precisely then ordinaryvisual techniques.

The thermoelasticity approach, based on simultaneous measurements of the mechanical work andof the concomitant heat, exposing two aspects of the deformation of the material (developed forpolymers (3|), was applied in investigating the fiber/matrix interaction in composites. Inparticularly, it was intended to expand our studies of poly-(etheretherketone) (PEEK)/carbon fibrecomposites (designated APC). The experiments were carried by a Thian-Calvet type deformationmicrocalorimeter [4].

First, the thermoelastic approach was applied for experimental and theoretical treatment of PEEKmatrix. The thermoelastic behaviour of PEEK was typical of the polymeric glass, in both theelastic and the plastic regions. The experimental deformation dependences of the energetic effectswere in accordance with Kilian's model describing the elastic and plastic deformation of apolymeric glass as a united process [5].

Consecutively, an investigation of model microcomposite samples (consisting of an isothermallycrystallized at 25°C J-Polymer matrix with carbon fibers) was performed. For thatmicrocomposite, after the said thermal treatment a transcrystalline layer was clearly observedalong the fibers. Testing was performed on a pure matrix film and on matrix with either onelongitudinal or two transverse fivers. The idea was to compare the thermodynamics of stretchingof the pure matrix and of the microcomposites, and to reveal the contribution, if any, of a

-« transcrystalline layer. Unfortunately, no meaningful difference in the energetic effects ofstretching was discovered between the samples, probably, because the fiber volume fraction was

1 too low to separate the contribution of fivers and transcrystalline layers from that of the matrix.However, the measurements of the heat of stretching allowed to describe the deformationbehaviour of the investigated samples more accurately, than routine mechanical forcemeasurements.

I REFERENCES

1 1. D. Hull, An Introduction to Composite Materials, Cambridge University Press, Cambridge,I 1981.J.

2. M. Narkis, E.J.-A. Chen and R.B. Pipes, Polym. Comp., 9, 245 (1988).

3. H.-G. Kilian, Th. Vilgis, Coll. Pol. Sci., 262, 15 (1984).

3. H.-G. Kilian, G.W.H. Hohne, Termochimia Ada, 69, 199 (1983).

4. J.A. Koene, B. Heise and H.-G. Kilian, J. Polym. Sci.: Polym. Phys. Ed.,27, 1235(1989).

I . I .

i

DEGRADATION OF POLYMERS BY HYPERTHERMAL ATOMIC OXYGEN

R. Vered*, G. Nahor*, G.D. Lempert*. G. Marom**, Y. Lifshitz*

* Applied Physics & Mathematics Department, Soreq NRC, Yavne, Israel

**Kasali Institute, Hebrew University, Jerusalem, Israel

Degradation of polymers by hyperthermal atomic oxygen and other hyperthermal species

occurs in a variety of practical systems including external surfaces of spacecraft in low

earth orbits (LEO), i.e. at altitudes of 200-800 km. The impact of a spacecraft orbiting at

8 km/sec with the residual atomic oxygen yields an equivalent oxygen energy of 5 eV

resulting with a significant erosion especially of polymeric surfaces.

In the present work the effects of hyperthermal species on two polymers commonly used

for space applications (Kapton H and Teflon FEP) were investigated. The polymers were

exposed to O+ and Ne+ influence of 1017 - 1019 ions/cm2 at energies of 30 eV and 20

keV. A variety of phenomena associated with the degradation of these polymers were

investigated including total mass loss release of gaseous fragments during bombardment

(RGA), surface morphology (SEM) and surface chemical composition (XPS).

The experimental data will be presented and the influence of energy and type of the

bombarding species will be analyzed. The relative significance of the collisional and

chemical effects for the different polymers will be discussed.

The relevance of the present study to space simulation of atomic oxygen (ATOX) effects

in polymers will be evaluated.

, 1 . 4

.$>

fTRANSCRUSTALLINTTY EM THERMOPLASTIC COMPOSITES AND ITS

INFLUENCE ON THEIR MECHANICAL PERFORMANCE

Nava Klein, Gad Marom

f* Casali Institute of Aplied Chemistry, Graduate School of Applied Science and

Technology, The Hebrew University of Jerusalem, Jerusalem 91904, IsraelThermoplastic matrix composites have been developed in recent years to replace thermoset

composites for a number of reasons including their higher fracture toughness and

unlimited shelf life. When a fiber is embedded in a thermoplastic semi-crystalline resin,

heterogeneous nucleation may occur. In a case where there is high density of nucleation

sites along the fiber surface, a columnar layer of crystals known as transcrystalline layer

will develop around the fiber.

Although the presence of the transcrystalline layer has been reported, the mechanism by

which transcrystallization occurs is not fully understood. Moreover, a method that will

predict its creation has not been offered yet.

Since the transcrystallization is known to be a nucleation-controlled process, it depends

strongly on thermodynamic conditions such as the crystallization temperature or the

cooling rate. Other factors, found to affect its appearance, are the topology and surface

coating of the fibre, the thermal history, thermal conductivity mismatch between fiber and

matrix, high surface free energy of the fiber and presence of stresses at the fiber/matrix

interface.

The distinct morphology of the transcrystalline layer leads to different mechanical

properties compared with the bulk resin. However, the effects of the transcrystalline

layer on the composite mechanical properties are still unclear, and so the role of a

•» transcrystalline interface in compositees is not conclusive.

The objective of the research was to discover the main factors that determined the

transcrystallinity process and the mechanism by which its presence affected the

mechanical properties of the composites. The kinetics of the transcrystallization process

in isothermal conditions were studied using samples of microcomposites on a hot stage,

examined by a polarizing microscope. The microcomposites consisted of either pitch-

based carbon fibers or aramid fibers, embedded in Nylon 6,6 resin. The kinetics data

were used to calculate energy parameters, using a modified heterogeneous nucleation

mechanism.

The ability to control the transcrystalline layer and, in turn, its influence on the

performance of composite materialsd would result in manufacture process optimization.

i. : \ i

POL VETH YLENE FIBRES - POLYETHYLENE MATRIX COMPOSITES:

PREPARATION AND PHYSICAL PROPERTIES

A. Teishev*, S. Incardona**, and G. Marom*

*Casali Institute of Applied ChemistryGraduate School of Applied Science and Technology

The Hebrew University, 91904 Jerusalem, Israel

**Department of Materials EngineeringThe University of Trento

Mesiano 38050, Trento, Italy

A major disadvantage of high-strength ultra high modulus polyethylene (UHMPE) fibers,

restricting their application in composite materials, is their chemical inertness, that

prevents their bonding to polymer matrices. The present research is an attempt to embed

UHMPE fibers (SPECTRA 900 and 1000) in high-density polyethylene (HDPE) matrix.

Because of the chemical similarity of the composite components good bonding at the

fiber-matrix interphase could be expected, while because of their different physical states

and melting points (melting temperatures are about 130°C and I50°C for the matrix and

the fiber, respectively) the molding of the composites is feasible. The effect of various

processing conditions on the ultimate material properties was also investigated, as it was

expected to determine the microstructure of the composite.

The matrix, the fiber and unidirectional composite laminae were studied using

thermomechanical analysis (TMA), differential scanning calorimetry (DSC), a hot stage

crystallization unit attached to a polarizing microscope and universal tensile testing

machine. The TMA showed negative thermal expansion of the fiber within the full

experiment temperature range. Three regions of contraction according to the values of the

thermal expansion coefficient were detected. DSC analysis of both fiber and composite

specimens did not reveal any appreciable difference for various thermal treatments. The

tensile strength and modulus values were close to those reported for the SPECTRA -

epoxy resin composite. A slight decrease of strength for the higher processing

temperatures was observed while the Young modulus did not change. The study of the

matrix microstructure did not give any proof of transcrystalline growth at the fiber-matrix

interphase even for chemical or plasma surface treated fibers, and the matrix washed in

different solvents.

A new material with impressive mechanical performance was prepared and analysed. The

results of the study confirmed that HDPE could be successfully used as a inatrix with

UHMPE fibres.

: i

STRUCTURE CHARACTERIZATION OF LASER PROCESSED WC/Co LAYERS

M. Boas*, M. Bamberger**

*Rafael, P.O.Box 2250, Haifa, Israel

**Material Engineering Department, Technion, Haifa, Israel

Laser surface cladding or similarly laser surface alloying can be utilized for creating a hard

layer on matrix having lower hardness. This will lead to the improvement of the surface

adhesive and abrasive wear properties and also corrosion resistance can be acquired to the

material surface. Laser alloying hardening processes have the potential for various

industrial applications with the advantage of causing lower sub-surface damage and lower

dimension distortions in comparison to other hardening techniques.

In the current research, metallurgical characterization was performed to surface layers of

low carbon steel alloyed with WC/Co. Laser alloying was carried out by powder

injection and by melting a pre-layered plasma sprayed coating. In the two alloying

methods, layers with various hardness level can be produced, depending on the working

parameters of the laser beam and the alloyed material properties. Layer hardness, phases

composition and the general structure depend mainly on the content of the alloying

elements. Less uniform structure accompanied with surface cracks and higher hardness

will result from high WC content. Lower carbides content will lead to more uniform

structure with still substantial hardness. Phases composition will be mainly influenced by

the laser working conditions and by the composition of the plasma sprayed which might

be quite different from this of the original powder.

t: MICROSTRUCTURE AND MECHANICAL PROPERTIES OF SiC

PLATELET/CORDIERITE GLASS-CERAMIC COMPOSITES

Rachman Chaim

j Dept. of Materials Engineering, Technion-Israel Institute of Technology, Haifa, Israel

Cordierite glass-ceramics reinforced by different volume fractions (0, 10,20 and 30%) of

SiC platelets were fabricated by mechanical mixing of appropriate powders, followed by

cold and hot-pressing above the glass transition temperature. Some of the specimen were

subjected to post-sintering crystallization treatments. The resultant sintered mierostructure

was highly textured within which the prismatic SiC platelets were oriented with their basal

planes perpendicular to the hot-pressing direction. The true porosity was dependent upon

the SiC content. The single-edge-notched-beam (SENB) fracture toughness and the

bending strength increased significantly v»ith the SiC content Fractography by SEM has

confirmed the crack-deflection to be a dominant mechanism which contributed to the

improvement in the mechanical properties.

fSURFACE ENGINEERING OF STEELS IN MOLTEN BORAX

a S. Bhagga Fazluddin*, A. Koursaris*, C. Ringas**, K. Cowie***i •Department of Metallurgy & Materials Engineering, University of the Witwatersrand,

South Africa

**MATTEK, CSIR, Cottesloe, Johannesburg, South Africa

***Metal Technology Engineering, Chris Street, Alrode 1451, South Africa

The formation of VC, NbC, and Cr-carbide coatings of steels immersed in molten borax

baths containing carbide-forming constituents has been known for some time. A study

was made of the formation of carbide coating on steel specimens treated in molten borax

baths containing V2O5. The prevalence of oxidizing or reducing conditions in the bath

was found to play a decisive role in the formation of the VC layer. The influence of

treatment factors such as time, temperature, and bath composition on the thickness of the

coating was investigated. Microstructural examination of coated specimens was

performed using optical and electron microscopy. Microhardness tests, X-ray diffraction

(XRD) and energy dispersive spectroscopy (EDS) analyses were carried out in order to

characterise the layers produced.

I ELECTRICAL RESISTIVITY OF 3104 Al-ALLOYS

t A. Stern*, L. Phillips**, A.H. Cahn**

| *Nuclear Research Center-Negev, POB 9001, Beer Sheva, Israel

? **National Institute of Standards and Technology, Gaithersburg, MD 20899, USA

The most characteristic single property distinguishing metals from other materials is that

of readily conducting electricity. It is not surprising, therefore, that the electrical

resistivity is frequently measured and used as a tool in metallurgical research. In the

application to the measurement of the temperature of 3104 aluminium sheets we utilized

the temperature dependence of the electrical resistivity of the material.

The electrical resistivity of samples taken from twenty 3104 Al coils supplied by 5

manufacturers, having composition variations allowed within the alloy designation, was

mesured at room and high (300°C to 400°C) temperature by the eddy current (EC)

method. The room temperature EC resistivity was compared to the 4 - point probe DC

measurements and a excellent agreement was found between the two methods. In our

analysis of the data we have assumed the validity of Matthiessen's rule, that the resistivity

of a dilute alloy is the sum of the resistivity of the pure aluminum at the specified

temperature and the resistivity contribution from alloying elements and from deformation.

The deformation contribution to resistivity, measured as 0.035 |i£2cm in annealing

experiment, was present in the room temperature samples, and assumed absent at high

temperature. The alloying contribution to resistivity (called also residual resistivity) is a

function of composition and the degree of solid solution of the alloying elements. To a

first approximation room temperature structure of 3104 Al alloy consists of an Al matrix

having Mg, Zn and Ga in solution and Si, Fe, Cu, Ti and V out of solution in form of

precipitates. Most of the Mn is out of solution in form of intermetallic precipitates and the

rest is in solution in the Al matrix. The amount of the Mn in solution was calculated from

the room temperature residual resistivity of the 3104 Al alloy using the values of residual

resistivities per 1% weight of the different alloying elements in solution and out of

solution. The calculated alloying elements in solution and out of solution. The calculated

amount of Mn(%wt) in solution is in the range of 0.23 - 0.42 and different for the five

manufacturers. As the amount of Mn in solution is process dependent, the different

manufacturers probably used slightly different procedures to produce the coils, yielding

different amounts of Mn in solution

DEPOSITION OF DIAMOND FILMS ON CEMENTED CARBIDES (WC + Co)

A.K. Mehlmann*. A. Fayer* and S.F. Dirnfeld*. Y. Avigal**, R. Porath***

* Department of Materials Engineering

** Solid State Institute

Technion-Israel Institute of Technology, Haifa 32000, Israel

***Iscar Ltd., P.O. Box 385, Maaloth, Israel

The possibility to use diamond films on cutting tools has turned the low-pressure

diamond deposition on cemented carbides into a field of large interest.

This research was performed with the aim to get quantitative estimation of the main

factors which affect the diamond layer quality; nucleation density, outward diffusion of

cobalt from substrate and interfacial stresses. The experiments were accomplished on

cemented carbide substrate (WC + 6% Co) using the hot filament CVD method and

CH4/H2 1% mixture.

The nucleation process was studied on polished and fractured surfaces. We investigated

the effects of ultrasonic pretreatment and deposition temperature on nucleation. The

deposition experiments performed on fractured substrates suggest that the main role in

enhancing nucleation is played by surface contamination.

The SEM images of substrates surface partially covered by diamond show that cobalt

particles strongly attack contiguous diamond crystals. The fact of cobalt influence

diamond deposition was confirmed by the different growth kinetics of diamond coating

on unetched and etched substrates. The etching was performed using a HNO3/H2O 1:1

solution.

It was found that when heating at 940°C in CH4/H2 1 % activated gas mixture a strong

etching effect of cobalt, probably by atomic hydrogen, is obtained.

The residual stresses in diamond films were measured by X-rays diffraction method. The

experimental results show that compression stresses take place in diamond coatings which

are essentially related to deposition temperature.

SOLID STATE SYNTHESIS OF CoAl AND NiAl 1NTERMETALLICS VIA HIGH jf

PRESSURE CONSOLIDATION OF FINE ELEMENTAL POWDERS

L. Farber and E.Y. Gutmanas

Department of Materials Engineering, Technion, Haifa, Israel

CoAl and NiAl B2 intermetallics were synthesized from consolidated to full density jj

micron size elemental powder blends (Co, Ni-AI). Consolidation was performed by cold

sintering (high pressure consolidation at ambient temperature) at pressures considerably

lower than those required for consolidation to full density of the prealloyed intermetallic

powders. Subsequent homogenization heat treatments resulted in solid state reactive (

synthesis of the corresponding aluminide. The microstructure and phase composition of

the aluminides obtained were studied employing X-ray diffraction, SEM/EDS and f

TEM/EDS. DTA experiments showed that at temperatures above 500°C self-propagating \

synthesis (SPS) of Co and Ni aluminides takes places accompanied by the formation of a

transient liquid phase. The SPS process is difficult to control and usually results in the

decreased density and cracking of the final product. To avoid the formation of the liquid :

phase, the first step of the synthesis heat treatment was performed at temperatures below

500°C. During this treatment the formation of intermediate CO, Ni-AI phases of different

stoichiometry, including CoAl and NiAl, was observed, the kinetics of the process being

controlled by the diffusion of components through these phases. Reactive diffusion *

processes in Co, Ni-AI powder systems were studied on model structures - an Al foil

partly or fully embedded in a Co or Ni powder and, vice versa, a Co or Ni foil/thin

sample embedded into an Al powder. Layered structures prepared from alternating thin

Al and Ni foils were also used in model experiments. It was found that the synthesis

process didn't go to completion at temperatures below 500°C. In order to obtain a one

phase equiatomic aluminide, higher temperatures were required. The presence of the

intermediate phase layers at former Co, Ni-AI powder particle interfaces allowed to

accomplish the synthesis without the liquid phase formation. The described approach to •*.

the synthesis of CoAl and NiAl may be used for production of close to net shape full }

density intennetallic parts. »

f

THERMODYNAMIC CONSIDERATION FOR SOLID STATE AMORPHIZATION BY

MECHANICAL ALLOYING

Y. Chakk, S. Berger, B.Z. Weiss

Dept. of Materials Engineering, Technion, Israel Institute of Technology, Haifa, Israel

Mechanical alloying (MA) is a high energy ball milling process. Powder particles trapped

between the colliding balls undergo micros true tural, compositional, and surface

morphology changes. Mechanical alloying is a solid state process which can lead to

various results such as amorphization of crystalline alloys, formation of intermetallic

compounds, creation of solid solutions from non-soluble elements, and reducing the grain

size to a nano-meter scale. The final product of mechanically alloyed powders depends

on the initial composition, microstructure.atomic size, and electronegativity.

In the present paper, a quantitative approach for determining the possibility of solid state

amorphization of bi-elemental system by MA is presented. The model is based on known

physical properties of the powder elements. This approach takes into considerations the

initial lattices and atomic sizes of the powder elements, their heat of mixing, and the

milling parameters. It gives the composition range where amorphization can occure for

specific milling parameters and the enthalpy change associated with it. This theoretical

approach was tested on various experimental data and the result will be discussed.

FACTORS AFFECTING THE QUALITY OF ELECTRON BEAM (EB) WELDS OF Al

1050 END CAPS TO Al 6061 TUBES

A. Stern*- **, I. Dahan* and D. Eliezer**

•Nuclear Research Center-Negev, Beer-Sheva, Israel

**Materials Engineering Department, Ben Gurion University, Beer-Sheva, Israel

An experimental study on automatic and autogeneous electron beam welding (EBW) of Al

1050 and caps to Al 6061 tubes (OD 10mm x lmm wall thickness), was carried out. The

composition of the bulk weld metal in dissimilar metal EB autogeneous butt welds

depends on the location of the beam axis in relation to the plane of joint faces. The effect

of varying the compositions of the fusion zone as a result of different EB positions (i.e.

the weld metal dilution) on microstructure, discontinuities and hardness of the weld joint

has been studied. Two sets of specimens, using 10 J/mm and 19 J/mm heat inputs have

been welded. In order to examine the role of the dilution on the properties of the weld

joint, transverse sections through the fusion zone and the HAZ were prepared for

metallographic observations under optical and scanning electron microscopes. Electron

probe microanalysis (EMPA) was used to determine the chemical composition of the weld

metal. Microhardness measurements, carried out at a load of 0.2 N, were used to study

the mechanical response of the joint to the welding parameters.

In this study, the following conclusions were drawn:

1. The most frequent weld discontinuities found in the fusion zone are porosity and

cracks. The extent of cracking and porosity was correlated to the dilution of the weld

metal, which in turn is influenced by the symmetry of the fusion zone.

2. A general increase in cracking and porosity occurrence was observed in the welded

specimens subjected to the higher heat input.

3. The hardness profiles of the fusion zone are directly related to the degree of dilution.

A significant increase in microhardness was observed in areas adjacent to fusion zone

line in the Al 6061 HAZ (above 100 HV, as compared with about 60 HV in the weld

metal and 80 HV for the Al 6061 tube). This result can be explained in terms of

recrystallization and precipitation reactions in the HAZ of the Al 6061 tubes.

HOMOGENIZATION OF LAYERED THIN FILMS UNDER ELECTRIC CURRENT

L. Klinger, A. Katsman, A. Levin

Department of Materials Engineering, Technion

Israel Institute of Technology, Haifa

Layered thin film structures are an essential element of modern devices in

microelectronics. An indispensable requirement with regard to these elements is stability

in electric and temperature fields. At the operating temperatures of layered thin films,

grain boundary diffusion occurs within each layer and between layers. Under the action

of electric current via the multilayer film, internal stresses are fomied in conductor layers

as a result of electromigration. The stresses that appear in adjoining layers are responses.

The stress gradient across the layered structure intensifies the interdiffusion between

layers which, in turn, accelerates homogenization of the layered structure.

In the present work we consider internal stress formation in a two-layer thin film on an

undeformed substrate under the action of electric current. Layer conductivities are

assumed to differ substantially. Stress relaxation may lead to growth of hillocks at the

outer surface. Where a conductor does not possess an outer surface, relaxation occurs by

interdiffusion - mutual penetration of material from one layer to another.

Diffusion equations describing the process were solved, taking into account the fluxes of

components caused by stress gradients formed during diffusion and also the process of

stress relaxation.

Stress distribution, constituent concentrations and their time dependencies were calculated

for a two-layered thin film structure. The velocity of the cathode edge as a function of

path length, current density and temperature was studied. The calculated

* MAGNETRON-SPUTTERED Co-DEPOSITED THIN n L M S AS A METHOD FOR <

f CONSTRUCTION OF MULTI-COMPONENT PHASE SYSTEMS

I. Goldfarb and D. Shechtman

• Technion-Israel Institute of Technology, Haifa 32000, Israel

The preparation of a series of alloy specimens that follow a full binary or ternary '

composition range is a difficult task if bulk specimens are made in large numbers.

In our method we prepare a continuous sample covering all composition range of a multi-

component systems, with the desired composition accuracy. Our method involves '

prismatically (Wedge-shaped) deposited alternating thin multi-layers of the desired

components in such a manner that the concentration gradient will be from 0% to 100% for •

each component. ]

In this study, the Au-Ag-Cu ternary system was chosen for its simplicity and application.

This diagram is characterized by phase separation resulting from the binary Ag-Cu

diagram, and by ordering reactions from the binary Au-Cu systems. Unlimited solubility

in all composition range takes place in the binary Au-Ag system. 30 tri-layered films, 12

nm each, were sputter-deposited in 55 Formvar-coated Mo grids. The overall thickness

was chosen to be thick enough for X-ray diffraction (XRD) and for suitable Energy

Dispersive Spectroscopy (EDS) analysis, but thin enough for Transmission Electron

Microscope (TEM). Mo was chosen as a substrate material for its inertness to Au, Ag

and Cu in the relevant temperature range. The substrate grids were arranged in a form of

close-packed triangle so as to give 55 differently-composed samples, covering an

isothermal section through the ternary phase diagram.

The investigation was proceeded in following stages:

1. Samples were deposited by means of magnetron DC-sputtering onto the substrates at

room-temperature, as described. \

i •2. The as-deposited samples were analyzed by XRD and EDS, in order to determine

their structure and composition. ,,

3. Samples were then homogenized by heat-treatment at low temperatures for various

periods of time, resulting in multi-phased equilibrium samples.

4. These samples were then analyzed again by XRD, and by TEM.

Based on these results, it is concluded, that the proposed method is an effective way for a ,,hconstruction of multi-component phase systems, }

.4.2

ELASTIC INTERACTION BETWEEN PRECIPITATES IN THIN LAYERS

R. Shneck*, M.P. Dariel* and A. Brokman**

*Ben Gurion University of the Negev, Beer Sheva, Israel

**Jerusalem, Israel

Our work is concerned with the effect of the elastic interactions on the precipitate

distribution within thin films. We shall present and discuss the solution of the elasticity

problem of a finite coherent precipitate in an elastic, isotropic and homogeneous layer. It

is well established that the elastic interaction between dilating precipitates vanishes in a

isotropic infinite matrix. The proximity of free surfaces induces, however, an attractive

elastic interaction between like particles that increases monotonically with decreasing

interparticle distance. The attractive interaction is maximal when the particles become of

equal size and it increases as they grow closer to the free surfaces.

The correlations that result from the elastic interaction in the thin layers generate a

tendency towards clustering of equal-sized particles. However, the self-energy of an

isolated precipitate decreases rapidly as it grows closer to the free surfaces favoring,at the

advanced stages of the precipitation, precipitate coalescence rather than clustering.

1 .4.3

GRAIN GROWTH IN COPPER-CHROMIUM MULTILAYERS

' U. Admon*. M.P. Dariel*- **, G. Kimmel*, J. Sariel*, A. Stechman*- ** andI L. Zevin**

*Nuclear Research Centre-Negev, POB. 9001, Beer Sheva, Israel

**Deparunent of Materials Engineering, Ben Gurion University, Beer Sheva, Israel

Copper-chromium multilayers with wavelength, k ~ 20 nm, were prepared by dual

magnetron sputtering on silicon substrates. The mutual immiscibility of copper andchromium ensures that the layers retain their individual character and that no interdiffusion

or reaction takes place between them at the deposition temperature. Low-angle X-ray

diffraction revealed a well defined one-dimensional copper-chromium superlattice and -*

allowed the accurate determination of the repeat distance, namely the combined thickness

of two adjacent layers. ,

High-an<:!c X-ray patterns showed the presence of a intense but broadened (111) Cu line,

suggesting a strongly textured layered structure. The absence of Cr diffraction peaks, in

spite of the presence of 30 % Cr, as indicated by EDS measurements, is attributed to the

nature of the chromium layers, a relatively high melting point metal. At the deposition

temperature, the Cr layers are either amorphous or nanocrystalline.

High temperature X-ray diffraction runs were carried out in the 300-620°C temperature

range, as a function of the length of the dwell time at the high temperature. The height of

the (111) Cu diffraction line increases with its concurrent narrowing, while the integrated

intensity stays relatively constant. The narrowing of the diffraction line is due to the grain

growth taking place in the copper layers during the high temperature anneal. The analysis

of the line narrowing as a function of the annealing time provides information regarding

the kinetics of grain growth within the multilayers. In principle, results obtained at

different temperatures allow to infer in the mechanism of copper mobility within the

multilayers, in particular, regarding the relative contribution of the bulk, grain boundary •

and surface diffusion effects.

Additional peak appear above 600°C. Preliminary interpretation suggests the nucleation 5

of chromium or chromium rich compounds. Additional experiments are underway to

determine the temperature range for chromium nucleation and grain growth within the

multilayered material.

The results establish the potential and scope of using multilayered metallic materials as

subject of study of nucleation and growth phenomena in thin metallic layers. f "

t . 4 . 4

I ELECTROMIGRATION IN THIN FILMS: TIME DEPENDENCE OF STRESS

I DISTRIBUTION AND HILLOCK GROWTH

f A. Katsman, L. Klinger, A. Levin, E. Glickman

| Dept. of Materials Engineering, Technion, Israel Institute of Technology, Haifa, Israel

^ This study is devoted to stress initiation and evolution due to electromigration in thin films.

The new element of the proposed analysis is explicit inclusion of the relaxation process

occurring through formation of hillocks near the anode end of the conductor line under

consideration. Calculation is based on Kirchheim's model in conjunction with the creep

equation which controls the rate of hillock formation.

Two cases are analyzed: (i) extrusion of material through a fixed aperture (e.g. in dielectric

coating); (ii) extrusion through an aperture whose size is time-dependent; in this case the

hillock zone size is a function of the stress distribution. It was shown that after a short

incubation period, the stress distribution can be calculated via a diffusion-like equation

with a source:

fO, 0<a,a a ~ ( ( E / n ) ( C T - a t ) , 0 > a t

where D a = D Q E/kT is the effective diffusion coefficient (E - modulus of elasticity, T) -

effective viscosity, <J| - the threshold stress). The time dependence of the stress

distribution (found from eq. (1)) are used for determination of the cathode edge velocities.

It is known that the displacement of the cathode edge determines the time to failure during

homogeneous electromigration. It was shown that for long path and high current density,

the stress distribution is substantially nonlinear and is time-dependent.

1.4.5

CERAMIC MATRIX COMPOSITES PRODUCED BY DIRECT MELT OXIDATION

E. Manor*, H. Ni**, C.G. Levi**, and R. Mehrabian***

*Department of Materials Engineering,Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel

**Materials Department, University of California-Santa Barbara,Santa Barbara, CA 93106, U.S.A.

***President, Carnegie Mellon UniversityPittsburg, PA 15213, U.S.A.

Ceramic Matrix Composites produced by direct melt oxidation can be designed to have

high toughness and good thermal shock resistance, as well as high stiffness, good wear

resistance and high temperature stability. Furthermore, the method allows production of

near net shape at a low cost. In the more general case, the high temperature oxidation

(T > 1200°K) of molten Aluminum with suitable alloying additions yield a continuous

AI2O3 matrix with interpenetrating three dimensional network of metal microchannels.

Favorable structure properties can be achieved by growing this "composite-matrix" into

preforms consisting of reinforcing particulates.

Characterization of the resulting composites included the volume fraction of SiC and

residual metal, the scale of the microstructural features, the composition of the metal

within the channels, and the porosity as a function of both temperature and SiC particle

size. The oxidation rate of a slightly modified A380 Aluminum alloy was significantly

enhanced by the presence of the SiC preform, with a tendency to increase with decreasing

particle size. The underlying mechanism involves: preform wetting and secondary

nucleation of AI2O3 on the particle surfaces, perhaps by reaction of the alloy with the S1O2

layer formed on the SiC.

The study was initiated with the objective of enhancing our understanding of the growth

of an Al2C<3/metal matrix into SiC preforms, evaluating the role of the preform on the

growth process and the origin of various microstructural defects, notably porosity and

chemical segregation.

I TENSILE BEHAVIOR OF ALUMINA CARBON/EPOXY LAMINATED SYSTEM

| Dov Sherman and Frederick A. Leckie

Department of Mechanical Engineering, University of California,*' Santa Barbara, CA 93206}•

Ceramics are attractive due to their superior mechanical properties. The elastic modulus

of ceramics is high, and the density is low. As a consequence, the specific modulus (E/p)

and strength (<Tult/P) are very htfi, and make the ceramics very attractive in light weight

structures. The hU) melting temperature of ceramics, the high creep resistance, and high

thermal shock resistance make the ceramic materials superior at high temperature

environment. Other properties, like high hardness, and wear and corrosion resistance

enable to withstand in hostile environment. HOwever, the fracture toughness of

ceramics, and the absences of R-curve behavior limit thir use in mechanical components.

As a result, reinforcement must be considered for high performance ceramics. A commoc

reinforcement is achieved by introducing embedded fiber, unidirectional, cross plies or

woven.

An alternative system is reported hete The composite is made of a multimaterial laminated

system consisting of alternating together brittle and ductile thin layers. The britlle, the

ceramics, is stiff and the ductile is stronger and has later strain to failure, and serves as

the reinforcement. This system is a new philosophy in reinforcement of brittle materials.

A thin alumina layers, alternating together with carbon/epoxy prepreg tapes.represents a

brittle ductile laminated system. This system is available for experimental study, is cheap

and can easily be obtained. It gives an excellent oppohinity to study the mechanical

behavior of brittle ductile laminated systems, and is a first step in investigatirehigh

"* ( ^performance ceramics.

Experimental studies of alumina carbon/epoxy reveal the potential of this type of

reinforcement. It is observed that the stress for first cracking in this system is much

larger than for embedded fiber reinforced brittle matrix composites. Another advantage of

such layered systerrys that the undamaged modulus and strength are nearly isotropic that

is significant when the material is subjected to biaxial stress state. In addition, multiple

fracture mechanism when loaded in the carbon fiber direction causes pseudo ductile

behavior of the system.

The mechanical behavior in tension is fully described. The influence of number of layers

is examined experimentally and minimum number of layers is set for maximum stress for

first fracture. Highly branched wide laminated system are compared with narrow system

to demonstrate the width effect in such laminates.

1/

PROCESSING OF AI2O3 - SiC POWDER 'NANOCOMPOSUES"

I. Levin and D.G. Brandon

Dept. of Materials Engineering, Technion-Israel Institute of Technology, Haifa, Israel

The mechanical properties of alumina based ceramics can be enhanced by the addition of a

small volume fraction of submicron SiC particles. The conventional method for

producing a such material is by hot-pressing. The purpose of the present work is to

develop pressureless sintering for high-density alumina with small additions of submicron

SiC particles dispersed in a high-purity matrix.

Green compacts were processed by attrition milling of the initial powders followed by

filter-pressing. Optimization of the processing parameters was designed to obtain green

compacts with high packing density. Introduction of SiC submicron particles as a wear

product of SiC grinding media during attrition of the alumina powder was investigated.

XRD quantitative analysis was used to determine the SiC content. Information about size

of the SiC particles and their distribution in the matrix was obtained by EDS mapping.

The influence of processing parameters on the green density of compacts will be

discussed.

2 .1 .3

GLASS-CERAMICS: OPTIMIZATION OF STRUCTURE, PROPERTIES AND

TECHNOLOGY

Rimma Khodakovskaya

IMI (TAMI) Institute for Research & Development Ltd

Glass-ceramics are obtained by the method of nucleated crystallization of glass. We have

investigated the regularities of this process including the kinetics and mechanisms of

phase separation of glass, phase transitions during its crystallization and relationship

between structure and properties of glass-ceramics.

With this aim we used different structural methods such as XRD, SAXS, TEM, EPR,

IRS, Neutronography, DTA, DTG etc. for the experimental study of the process and

materials.

The specific objects of our research were glass-ceramics based on cordierite, mullite,

quartz-like solid solutions (MgO-Al2O3-SiO2 system) and (J-eucriptite and (i-spodumene

solid solutions (Li2O-Al2O3-SiO2 system).

The effects of the main factors controlling the process, namely: temperature and redox

conditions of glass melting, regime of crystallization, pre-crystallization heat-treatment,

small additives of extraneous oxides, concentration of nucleating agents were elucidated

and as a result, methods for optimization of structure, properties and technology of glass-

ceramics were established.

The features of the crystallization and sintering of glass powders and their mixtures with

crystal were elucidated. As result we could broaden the range of glass-ceramics

compositions, using ones outside the glass-forming ranges, by applying powder

(ceramic) technology.

We propose a novel principle of formation of glass-crystalline structures by self-heating

reactions, which take place during the sintering of powders with special additives. We

have applied this principle for obtaining mullite glass-ceramics and also high-temperature

coatings.

A large group of glass-ceramics with valuable properties was thus developed, based on

both glass and ceramic technology. These materials are characterized by high strength (up

to 6(X) MPA after thermal-chemical strengthening), thermal expansion coefficient over a

wide range of values (from 100-10"7 K"1 to 200-10"7 K-1, among them materials with a

near to zero), high thermal shock and chemical resistance, low dielectrical losses

(< 5-10"4), dielectrical constants of 5-25, controlled porosity, bioactivity.

?. 1 .4

MICROSTRUCTURAL AUDITING TO TRACEABLE STANDARDS IN THE PCDRIVEN QUALITY CONTROL LABORATORY

Brian Bousfield

Technical Marketing Manager, Buehler Europe Ltd., Coventry, England

ABSTRACT

Total information management throughout all aspects of a manufacturing process, from

user material through production and sales, can best be managed via some form of file

server acting as a director of operations.

The quality control laboratory although operating with individual computers will

inevitably be linked to the file server. The implications of this and the opportunity it

affords to update our thinking in the subjective black art of surface preparation for

microstructural analysis will be investigated.

SITUATION

Microstructural analysis is subjective, the surface preparation method or recipe is often the

result of a committee driven "round robin", the results being empirically derived, the

emphasis on machine automation without control being fraught with pitfalls. There are no

standards, no statistical means of auditing and the results are not traceable. Finally and

perhaps in consequence there exists no formalised training programme for technicians

specifically involved in surface preparation of materials. This paper therefore will address

these problems and will use as an example the work carried out on a recent European

vocational training course held in the UK (Dec. 1992). The subject of the course was

"Auditing to Traceable Standards - Plasma Spray Coatings". Integrated within this work

will be the logistics of the PC driven quality control for total information management.

c

THE EFFECT OF TRAPPING AND RELEASE PROCESS ON THERMONUCLEARFUSION REACTORS PERFORMANCE

E. Abramov

Department of Materials Engineering, Ben Gurion University, Beer Sheva, Israel

and

Nuclear Research Center-Negev, POB 9001, Beer Sheva, Israel

Trapping and release processes occur during the operation of thermonuclear fusion reactor

are reviewed. A theoretical study have been conducted to quantify trapping parameters

under the relevant conditions. The results show that large quantity of hydrogen isotopes

atoms will be accomodated in trapping sites at relatively high binding energy. This will

drastically affect the fuel, i.e. hydrogen isotopes, balance.

A large scale experimental study was carried out in order to verify the theoretical findings.

Hydrogen trapping and release parameters have been measured over wide range of helium

pre-implanted samples. These samples represented the materials which will behave as the

first wall of fusion reactor after different aging duration.

An unexpected phenomenon of enhanced helium release due to hydrogen introduction

was observed. This behaviour will damage the plasma purity and therefore the reactor

performance might be affected.

? . ? . 2

M

1

I

BMTERFACIAL EFFECTS IN THE PRESENCE OF HYDROGEN IN Al / AI3T1 / SiC

G. Solovioff and D. Eliezer

Ben Gurion University, Department of Materials Engineering, Beer Sheva, Israel

Dispersion strengthened, elevated temperature aluminium-titanium alloys derive their

strength and thermal stability from the presence of dispersed nanometer-size particulates

which effectively impede dislocation motion during deformation. The strengthening

characteristics of these particulates at elevated temperatures are dependent on their ability

to resist coarsening. Among the family of transition metal, high temperature alloys, Al-Ti

alloys are actively being studied due to their attractive combination of elevated temperature

properties. In addition, AL-Ti alloys are being studied as potential candidate matrix

materials in metal matrix composites (MMCs) in an effort to further increase the modulus

and the strength. There is definitive proof that hydrogen can interact with any number of

features commonly found in most structural alloys, including point defects, dislocations,

grain boundaries, particles and voids. In the present study, spray atomized and

co-deposited Al/Al3Ti/SiC were characterised following hydrogen charging, in order to

investigate the effects on microstructure and in the Matrix-Particles interface. The

cooperative relation between microscopic distribution of hydrogen and fracture

morphologies will be discussed.

it

2 . 2 . 3

I*A NEW MATHEMATICAL APPROACH BASED ON THE CIRCULAR DIAPHRAGM

TO EXPLAIN THE BLISTER EFFECT ON IMPLANTED METALS

D. Moreno*, E. Abramov* and D. Eliezer**

*NRCN, Beer Sheva, Israel

**Dept. of Materials Engineering, Ben Gurion University , Beer Sheva, Israel

The deformation and partial exfoliation of surface layers due to hydrogen and/or heliuminteraction with metals has been the subject of considerable research. Blister formationdue to the build-up of induced gas into the metal was investigated widely in diverse metalsand alloys. However there is no consensus as to the driving mechanism behind thisphenomenon. Recently, a new approach on the blister formation phenomenon has beendiscussed by means of the mathematical solution on a uniformly loaded circular plate withclamped edges (circular diaphragm).

It is general accepted that the blister formation depends strongly on the metal/alloy surfacetemperature, crystallographic orientation and on the energy and dose of implantation. Inthe present investigation we found that the blister formation depends on the mechanicalproperties of the material and the near surface concentration of the implanted gas, whichdepends on the crystallographic orientation by means of the stopping power of theimplanted atom. We assume that both the mechanical properties and the penetration of thebombarded atoms depends strongly on the temperature of implantation.

In order to obtain diverse depths and concentrations of gas, based on the Pearson IV,helium was implanted at different energies and doses at the same temperature. Theirradiation was carried out using the MEIRA (The Soreq high output isotope separator-Israel). Sample groups of, 1) annealed copper polycrystal, 2) single crystal in theprincipal directions <001>, <101> and <111>, and 3) Cu-2 Be-o.2 Co after diversethermomechanical treatment in order to obtain mechanical properties, had been implantedat a specific dose among 2xlO17 - 2.3xlO18 He/cm2.

The depth profile was analysed by secondary ions mass-spectrometer (SIMs). Thesurface morphology was analysed using a scanning electron microscope (SEM).Representative histograms of the blister size distribution were carried out, based on alarge number of micro graphs.

In almost all models, blister initiation starts from the assumption of excessive growth oflarge gas bubbles either by the agglomeration of clusters or by the coalescence of smallbubbles. Growth of large gas bubbles causes the transport of residual interstitial atomsby dislocation loop glide toward the surface. The atom movement becomes possiblebecause helium and vacancies coalesce in bubbles and tend to build-up large cavitiesparallel to the surface. The reported model is based on the fact that at certain depths fromthe surface the pressure in the cavities approaches the yield stress of the metal andblistering will start. The thickness of this Film depends on the mechanical properties ofthe specific metal. Once the blister cavity is formed, the deformation of the thin film toform a blister cap on the build up of the pressure in the cavity which depends on theimplanted dose.

The present model can be concluded by saying that the thickness of the blister's capcannot be correlated with the projected range of the implantation as assumed by otherauthors elsewhere. The helium concentration needed to build up a pressure to createblister in a depth which is close to the projected range is higher than the implantedconcentration and the edge of the circular skin where the maximum stresses are developedand the fact that at high implantation energy (large projected range) the bursting of theblisters occurs by multi layer caps support the present model.

2 . 2 . 4

IHYDROGEN EFFECT IN INTERMETALLIC TITANIUM - ALUMINIDES ALLOYS

J. Haddad, D. Eliezer

Ben Gurion University, Department of Materials Engineering, Beer Sheva, Israel

The titanium aluminides basically are of two generic types: the ordered hexagonal close

packed Ti3Al (012) and the ordered face centered tetragonal TiAl (y).

The low density ordered intermetallic titanium aluminides, based on Ti3AI and TiAl have

drawn a lot of research attention mainly due to their favourable elevated temperature

properties. Because of their ordered crystal structures both families of alloys have very

attractive elevated temperature strength characteristics but their Achilles heel is low

ambient temperature ductility.

Ternary alloying has overcome the problem of low temperature brittleness of both alloys.

Niobium additions improve the ductility of alpha-2, and the ductility of gamma is

improved by vanadium additions. Hydrogen embrittlement of titanium alloys, although

most often associated with a single form of degradation (hydride formation) can be very

complex, and very little understanding presently exists of the hydrogen interaction with

the titanium-aluminide phases.

Understanding of ductility and fracture behaviour is still emerging, as is knowledge of

environmental effects such as hydrogen embrittlement This study investigated the effect

of hydrogen charging on the phase changes and the hydride formation at room

temperature on Ti-48Al-lV at.% (Ti-48-1), and on Ti-25Al-10Nb-3V-lMo at.% alloys.

2 .2 .5

fI

i EXTREMELY SMALL CRYSTALS IN MULTI LAYERED C.V.D COATING OFTiC + TIN AND THEIR EFFECT ON THE PERFORMANCE OF CUTTING TOOLS

Reuven Porat, Natalie Arishkevitch, Avi Geltz

ISCAR LTD., Tefen, Israel

In the process of coating it is known that one of the useful combinations for coating cutting

tools is to use a triple layer of TiC + TiCN + TiN. This combination gives combined wear

protection. TiC is a good adhesive wear resistant which protects the cutting tool from

flank wear and TiN is a diffusion barrier wear resistant which protects the cutting tool from

crater wear.

While we increased the number of coating layers to achieve the same coating thickness we

got the advantage of higher tool life in machining steels. However, aside from having

higher wear resistance, using this combination also helps us to increase efficiency of the

machining process by increasing the cutting speed. The explanation for this advantage of

wear resistance and the capability to withstand high cutting speeds can be explained by the

multi layer interruptions, as these interruptions of the wear mechanism cause a halt in the

wear procedure. This multi coating layer can reduce and even neglect the effect of the

substrate properties on the behavior of the coating, i.e., this combination is the best barrier

diffusion for cobalt and carbon from the substrate to the coating, so the properties of the

coating are unaffected by the properties of the cemented carbide substrate.

Another advantage is that while in single layers, increasing the thickness of the coating

causes a reduction of the good mechanical properties, such as transverse rupture strength,

and increases the sensitivity for fractures. In this case, the multi layer coating behaved like

a stopping mechanism to eliminate propagation of the cracks, so that the thick coating

behaved like a thin coating enabling all the mechanical properties of the substrate to remain

with only small reductions in the mechanical properties.

By using multi layers we can increase the rate of deposition. In the beginning of every

coating process the rate of deposition is extremely high, after which gradually reaches a

much slower pace. By starting each layer from the beginning, and having higher amounts

of layers, we succeed to increase the deposition rate, and achieve greater efficiency in the

crystal growth rate.

In this paper we represent tool life of C.V.D. coated cutting tools, in machining steel with

different cutting speeds and comparison between coated cutting tools with multi coated

layers, to single layers.

2.3.

ELECTROCHEMICAL DEPOSITION OF ALLOYS OF GRADUATE COMPOSITION

Fe/Cu

R. Interter and Yoseph Yahalom

Compositionally modulated alloys exhibit greatly altered properties relative to the pure

component of their homogeneous alloys. The mechanical and magnetic properties of

these alloys are of particular interest. These properties are highly dependent on the

individual layer thickness of the composite. These alloys have been usually deposited by

vapor deposition or by ion sputtering.

A system of special interest is Fe/Cu since iron and copper do not dissolve in each other at

the ambient temperature. If each component should preserve it's structure a clear interface

boundary would be expected between the layers.

It was the purpose of the present work to develope a method that would produce foils of

modulated Fe/Cu alloys by electrodeposition. The procedure used was based on the

Yahalom Zadok method for deposition CM A by electrochemical means. By this process

an ordered alloy of two metals in alternated layers is built. This process uses a pulse

plating technique in which the less noble metal is plated at a lower potential followed by a

step in potential to the deposition value of the nobler metal layer. The deposition of the

two metals is done from the same solution while the more noble metal is in a low

concentration compared to the less noble metal in order to limit by diffusion it's

deposition during the deposition of the more active metal. By repetition of this process

the compositional modulated layer is formed. Deposition of modulated structure of Fe/Cu

by square pulse is problematic. However the iron layer dissolves when the potential is

switched from the deposition potential of iron to that of copper. Means to overcome this

difficulty have been developed in the present study.

An electrolyte containing an inhibitor for iron dissolution was used. More importantly the

gradual pulse technique was used for formation of Fe/Cu compositionally modulated

alloys. X-Ray diffraction of a deposit with 100 A layers confirmed the presence of iron

in the sample in BCC structure.

Auger analysis of CMA with designed 100 a layers indicated that iron is present at an

average concentration of about 10% indicating a low current efficiency for iron deposition

under the pulsing conditions. The modular structure of the Fe/Cu layers cannot of course

be revealed in the Auger profile since it is below the resolution of the instrument.

2 . 3 . 2

THE INFLUENCE OF A THIRD ELEMENT ON THE INTERFACE RACTIONS IN

METAL MATRIX COMPOSITES (MMQ: Al - GRAPHITE SYSTEM

D. Lotker*, J. Pelleg*, D. Fuks*,M. Ganor**, O. Yeheskel**

•Department of Material Engineering, Ben Gurion University of the Negev,Beer Sheva, IsraeJ

**Nuclear Research Center, Negev, Beer Sheva, Israel

First principal calculations have indicated that reaction between fiber and metal matrix can

be reduced to a large extent, or even eliminated when appropriate solute in small quantities

is incorporated in the MMC. In the Al-graphite (gr) composite system interface reactions

were observed by different researches, when such an MMC is maintained at sufficiently

high temperatures. Such reactions may occur either during the preparation of such

composites or during thermal treatment. We have produced Al-gr specimens by infiltration

by molten Al under pressure in graphite molds at a temperature of 775°C. Silicon at a level

of 0.5% was used as the addition to reduce the reactions at the fiber-metal interface.

Control specimens without silicon were also prepared. The specimens were characterized

at all stages by X-ray diffraction to see if AI4C3, which is the reaction product, was formed

in the above system. No presence of AI4C3 was found in the specimens with the silicon

addition, where's appreciable amounts of this phase were found in the control specimens.

The results of the metallographic examination by SEM and optical microscope will be

discussed. The kinetics of reaction zone formation in this type of specimens will be

presented.

2 . 3 . 3

DIAMOND-LIKE CARBON FILMS:PREPARATION, MICROSTRUCTURE - PROPERTY RELATIONSHIP

A. Raven*, L. Martinu**, J.E. Klemberg-Sapieha**, and MR. Wertheimer**

*NRC-Negev, Division of Chemistry, P.O. Box 9001, Beer Sheva 84190, Israel

**"Groupe des Couches Minces" (GCM) and Department of Engineering Physics, EscolePolytechnique, Box 6079, Station "A", Montreal, Quebec H3C 3A7, Canada

Despite great interest in deposition of crystalline diamond, diamond-like carbon (DLC)films are also considerably important. The main reason for this is the possibility ofpreparing homogeneous, dense, chemically inert films with low friction coefficient, atlow substrate temperature (below 200°C) and over large areas.

Deposition of DLC from hydrocarbon fed gases in low pressure glow discharge hasbecome a widely used method of preparation. During growth, the layers are subjected toion bombardment, controlled by the difference between the plasma potential and thenegative dc bias voltage at the sample surface. The resulting dense films are usuallycharacterised by a sp2/sp3 hybridization ration of ~0.4, by hydrogen concentration in therange 20-40 at.%, optical gap 0.8-1.5 eV, refractive index 1.9-2.2 and density1.5-1.8 g/cm3 (1-3].

Based on the comparison of hydrogen concentration values determined by the nuclearelastic recoil detection (ERD) technique with infrared spectroscopy data, microhardnessand density measurements, it was found that the DLC films can be distinguish to threedifferent microstructural categories [1], namely: (a) hard hydrocarbon, with hydrogenpredominantly unbonded, which is typically deposited under high (> 200 eV) ionenergy, but lower ion flux; (b) hard hydrocarbon, with hydrogen predominantly bonded,this material being deposited under high ion flux, but low (~ 100 eV) ion energy, and (c)a mixture of hard hydrocarbon and polymer-like component, grown under high ion fluxbut low ion energy (< 20 eV).

The current investigation in deposition of DLC films has been motivated in order tocorrelate between processing, microstructure and properties (microhardness, density,adhesion, friction coefficient), and to develop some understanding regarding those issues.

1. A. Raven, L. Martinu, S.C. Gujrathi, J.E. Klemberg-Sapieha, and M.R.Wertheimer, Surface and Coatings Technology (in press).

2. L. Martinu, A. Raveh, A. Domingue, L. Bertrand, J.E. Klemberg-Sapieha, S.C.Gujrathi, and M.R. Wertheimer, Thin Solid Films 208, (1992) 42.

3. A. Raveh, L. Martinu, J.E. Klemberg-Sapieha, and M.R. Wertheimer, J. Vac. Sci.Techno!. A 10. (1992) 12.

2 . 3 . 4

PATTERNING OF SUPERCONDUCTING YBCO FILMS

M. Riabkina-Fishman, J. Zahavi

Israel Institute of Metals, Technion, Haifa 32000

Development of lithographic techniques for patterning YBCO superconducting films to

the required configuration would represent an important technological achievement that

would allow the incorporation of this type of superconductors in microelectronic devices.

The necessary patterning precision could be achieved by conventional litography

techniques used in microelectronics industry, but the wet treatment involved in

lithography methods is detrimental to the conductivity of TBCO films and therefore this

approach is not optimal.

There is a different approach to the patterning of YBCO films. This approach takes an

advantage of the fact that superconducting properties of YBCO films are a function of the

substrate type and that only an epitaxial growth producing oriented YBCO films with

Cu-O planes parallel to the substrate surface will result in superconducting film with a

high critical temperature.

The principle is to use a substrate which is known to favor epitaxial oriented growth of

YBCO film and deposit on it an amorphous or polycrystalline layer. Then this layer must

be processes by an appropriate precision lithography technique in order to expose areas of

substrate in the desired shape and size. At the third stage YBCO film is deposited on this

processed substrate. The deposited YBCO film, while covering the whole surface of

such a composite substrate, would possess superconductivity only in the areas where

original substrate was exposed prior to YBCO deposition and would be insulating where

the intermediate layer was preserved.

SrTiO3 (100) single crystals were used as a substrate and amorphous SiO2 films 2000 A

thick were deposited as an intermediate layer. The results of resistivity measurements on

patterned and unpatterned films showed that the patterned film had only slightly lower

onset anil critical temperatures (Tc = 88°K instead of 90°K).

AMORPHOUS DIAMOND-LIKE-CARBON FOR MIS ANS MIM DIODES

M. Alaluf, D. Aizenman and N. Croitoru

Department of Electrical Engineering-Physical Electronics, Tel Aviv University, Israel

Amorphous Diamond-Like-Carbon (DLC) films were deposited by r.f. plasma system in

methane (CH4) environment. The amorphous film was found to have a diamond structure

(TEM micrograph) with hardness of 4800 knoop. It was found that the film is

semiconducting with an energy gap of 2.7 eV, a typical resistivity of 108 Qcm and

measured optical transparency in the visible and mid-IR light. Rectifying Al/DLC/p-type

silicon and A17DLC/A1 diodes were fabricated. Electrical measurements of current-

voltage (I - V), capacitance-voltage (C - V) characteristics and the temperature dependence

of the current (I - T) were measured. The I - V and the I - T measurements shows two

conducting processes: a) ohmic dependence at low electric field (E < 1.2 x 104 V/cm) and

b) Frenkel-Poole emission type with low barrier height (<|>m = 0.37 - 0.44 eV) at high

electric field (E > 1.2 x 104 V/cm). These processes are typical behavior for Metal-

Insulator-Semiconductor (MIS) and Metal-Insulator-Metal (MIM) diodes.

r

f

2 . 4 . J

I BARIUM NONATITANATE DIELECTRIC MINIATURE RESONATORS FOR

I MICROWAVE CIRCUITS

? Goldstein A., Kravchik M., Stancovsky V., Belov V.

/. Israel Ceramic and Silicate Institute

t-; Technion City, Haifa, 32000

Ceramic materials with intermediary constant values offer the possibility to produce

millimeter size resonators of high quality. The low size compared to that of the traditional

Invar alloy cavity resonators makes the ceramic resonator a natural choice for a variety of

electronic systems operating in the gigahertz frequency region, mostly for applications

related to tele-communications.

Materials having compositions located in the titania-rich region in the BaO-TiO2 system

were shown to possess the properties required for the production of high quality

resonators. The relevant parameters are the dielectric constant e, the quality factor Q, and

the temperature coefficient of resonance frequency TC. Their values are determined by

the phase composition, microstructure, nature and amount of impurities.

The objective of this investigation was to determine the technology enabling one to obtain

resonators with optimal dielectric properties. Various powder preparation and processing

methods, green body formation techniques, thermal treatment schedules and the influence

of dopants like Sn and Mn were examined and correlated. The phase and chemical

composition and the sintered specimens' microstructure were investigated too. The

values of £ and tg5 (Q) were measured at 1 and 10 MHz (preliminary testing).

Specimens with a bulk density close to the theoretical value, containing only dibarium

nonatitanate phase were obtained. Those specimens exhibited values of e about 40 and of

tg5 less than 2 x 10"4. Resonators based on this material are presently being tested.

2.4.4

CORRELATION BETWEEN ELECTRICAL PROPERTIES AND STRUCTURALCHANGES IN Sb IMPLANTED SiixGex LAYERS

Z. Atzmon*, M. Eizenberg*. J.W. Mayer**, Y. Shacham-Diamand**, F. Schaffler***

*Dept. of Mat. Eng. and Solid State Inst., Technion, Haifa 32000, Israel.

**CornelI University, Ithaca, NY 14853, USA.

***Daimler-Benz AG, Ulm Research Center, D-7900 Ulm, Germany.

Electrical properties of Sb implanted strained Si/-xGex alloy layers are reported. Two sets

of Sii-xGex epilayers with compositions of x = 0.08 and 0.18, MBE grown on (100) Si

substrates, were implanted at room temperature with Sb+ ions at energies of 200 and 100

keV, respectively, and doses of 1013 and 1015 cm-2. These alloys were heat-treated in a

rapid thermal annealing (RTA) system at temperatures between 500 and 900°C for

durations between 5 and 600 sec. Secondary Ion Mass Spectrometry (SIMS) and

Spreading Resistance Profiling (SRP) measurements show that Sb implantation with a

does below the critical value for amorphization (1013 cm"2), formed a p-type region upon

annealing at 500°C. Only higher temperature anneals transformed the implanted layer into

the expected n-type doping. Maximal values of electrical activity (45 ± 10%) and

mobility were obtained in this case only at temperatures around 8OO-9O0°C. For the high

does implantation (1015 cnr2) it was found that the highest activation efficiency was

obtained at 500-600°C. The maximal electrical activity at the implantation profile peak

was 50-60%, a value which is six fold larger than the maximum solid solubility of Sb in

Si at the annealing temperature. However, the electrical activity in the end-of-range

(EOR) region was very low, probably as a result of unannealed point defects that

produced the p-type region at the low dose implantation.

2 .4 .5

SIMULATION OF HYDROGEN ISOTOPES DIFFUSION THROUGH METALLATTICE CONTAINS A CONTINUOUS ENERGY TRAPS

E. Abramov*- ***, N. Yakobovitch**, E. Berman*** and D. Eliezer ***

*Nuclear Research Center-Negev, POB 9001, Beer Sheva, Israel

**Israeli Air-Force, Tel Aviv, Israel

***Department of Materials Engineering, Ben Gurion University, Beer Sheva, Israel

A unique computer code DIFFTRAP have been developed to solve diffusion equations

when continuous energy traps exist. DIFFTRAP enables simulation of light atoms

diffusion through metal lattice contains any known distributed traps under general initial

and boundary conditions. The advantages of DIFFTRAP in comparison with other

previously exist codes is described.

An application of DIFFTRAP for the case of hydrogen trapping near or around helium

bubbles is presented. The simulation of thermal desorption experiment using DIFFTRAP

is shown.

The desorption curve simulated by using continuous energy traps is compared to those

resulting by using discreets energy traps.

DIFFTRAP can be used to improve the estimation of hydrogen isotopes recycling

between the plasma and the walls of thermo-nuclear fusion reactor.

3 . 1 . J

i.C SURFACE MECHANOCHEMISTRY OF CRYSTALLINE SOLIDS

E. Gutman

Dept. of Materials Engineering, Ben Gurion University of the Negev, Beer Sheva, Israel

Interactions of crystalline solids with an environments and one with another are going

through an influence of solids stress state which is named mechanochemical effect.

Mechanochemical systems behave as an open nonequilibrium systems. Nonlinear

synergistic effects of surface and volume interactions are likely. The structure of

mechanochemical system has hierarchical, heterogeneous self-correlated type and it is

controlled by the minimum entropy production principle.

The following in fundamental principals of solid mechanochemistry new notions were

introduced. These are mechanochemical (mechanoelectrochemical) activity of substance,

chemical potential of dislocations and "dislocation lattice" in a crystal, affinity of plastic

deformation process, dislocations flow. This made possible to estimate a connection

between chemical potential of solid atom and dislocation, also describe kinetic equations

for mechanochemical phenomena. Generally, the entropy production of the such system

consists of minimum three main terms which are corresponding to three irreversible

processes: deformation, chemical reaction and solid dispersion. These processes are

developing, for example, during surface solid treatment, stress corrosion, solid-state

synthesis, powder sintering, preparation of ultrafine-grained powders, amorphization by

milling, applications of disintegratory technology, etc.

In this paper the basic theoretical notions of mechanochemistry are reported as well as

some of its practical applications.

A new effect of metals and minerals plastification, that we called "chemomechanical

effect", enables to propose methods for the mechanochemical surface treatments of

metals, alloys and minerals. This effect was a theoretical phenomenon followed by

experimentally proved phenomenon, as additive plastic flow of solid under chemical

(electrochemical) reactions on its surface. The chemomechanical effects was displayed in

mineral (calcite) single crystal dissolution by appearance of mechanical twins and their

growth from microhardness indentation and in metal (iron) single crystal by the

appearance of jogs of slip-band on microhardness indentation faces. For engineering

materials we developed a special method for the measurement of depth penetration

(hardness) of a needle-shaped indentor into surface that is polarized from the potentiostat.

The determination of chemomechanical effect allows the evaluation of the role of the

autocatalytic mechanism of fracture for the control of chemical resistance, and the

development of new material treatment technologies (as wet-drawing, mechanochemical

cleaning of metals, grinding and dispersion of minerals, drilling, etc.).

f. NONISOTHERMAL EFFECTS DURING THE MAES CRACK PROPAGATION IN

I BRTTTLE MATERIALSi% E. Druinsky*, L. Levin*, R. Arone**, A. Klyuch*i? *Department of Materials Engineering, Technion, Israel Institute of Technology, Haifa; 32000, Israel

**Israel Institute of Metals, Technion, Israel Institute of Technology, Haifa 32000, Israel

The classical criterion for a brittle fracture of solids is given by the Griffith theory whichhas been developed and modified by Orowan and Irwin for the case of small ductilestrains at the crack tip. A generalized Griffith-Orowan-Irwin's concept was formulated inthe terms of energy balance, that leads to equality between stress intensity factor andfracture toughness.On the other hand, in quasi-brittle materials the main crack may propagate by a thermallyactivated mechanism [1]. This process can be analyzed in the frame of the chemicalkinetics approach and described by the rate theory [2]. The last leads to the Arrheniustype dependence for the crack velocity [3]:

. kTv L

where T is temperature, k and h are the Boltzmann's and Plank's constantscorrespondingly, L is an activation length and E+ is an activation energy [4]:

E + = < x K * c ( l - K / K 1 ( / (2)

Here a and [i are some constants, K is the current value of the stress intensity factor,is fracture toughness of material, Kic depends on temperature and K - on the appliedstress. By analogy with [4] it is assumed that E+ is temperature and stress dependent.Usually the case of uniform sample temperature is analyzed. However such assumptionis only an approximation. The presence of the plastic zone at the crack's tip causes aconsiderable heating, which was found experimentally for several materials (steels,polymers, etc.).In the present work a model foe analysis of the influence of the heating effects on themain crack's propagation velocity in brittle is proposed. (1) is taken as the basisequation, but the temperature changes must be considered at the crack's tip. The solutionof the heat conduction equation for this case leads to the following expression for thetemperature at the crack's tip (Tf):

' T ^ T O + TQCV/U)1/2 (3)where To is the ambient media temperature, U = 2a2 / Rp, a

2 is the thermodiffusivitycoefficient, Rp is the plastic zone size and TQ is some constant having the temperaturedimension.The combined solution of (1-3) defines the self consistent equation for "renormalized"dependence of crack's growth velocity.This solution leads to the existence of two temperature regions of crack propagation:i) considerable crack acceleration region at low temperatures [5],ii) crack dampfing and arrest region at high temperatures.

1. A.S. Argon, Scripta Metallurgica, 16 (1982) 259-264.2. S. Glasstone, K.J. Laidler and H. Eyring, Theory of Rate Processes, McGraw-Hill,

NY, 1941.3. A.S. Krausz, K. Krausz, Fracture Kinetics of Crack Growth, Kluwler Ac. Publ.,

1989.4. E.R. Fuller Jr., R. Thompson, J. Mat. Sci., 15 (1980) 1027-1034.5. E.I. Druinskii, Sov. Phys. Solid State, 32 (1990) 1853-1858.

THE EFFECT OF TIN AND NICKEL ADDITION ON THE ENVIRONMENTALBEHAVIOUR OF SINTERED DUPLEX STAINLESS STEELS

A. Sharon and D. Itzhak

Department of Materials Engineering, Ben Gurion University, Beer Sheva, Israel

The environmental behaviour of Duplex stainless steel containing additions of elemental

tin or nickel powders has been investigated. Open circuit potential measurements a well

as potentiodynamic tests were carried out for each sample immersed in 1N H2SO4 at room

temperature.

It is concluded that elemental additions of tin powder to the Duplex stainless steel

improves considerably the corrosion resistance of the specimen rendering an

environmental behaviour very similar to the wrought or cast Duplex steel.

Addition of nickel powder to the same Duplex powder does not show any significant

contribution to the corrosion resistance of the sintered specimen.

A substantial change in the pore morphology of specimen containing tin powder has been

observed when increasing the additive content.

A smaller change in the pore morphology of powders containing nickel additive has beenobserved.

Metallographical and S.E.M (Scanning Electron Microscope) observations have been

carried out and correlated to the environmental behaviour.

3 . 1 . 4

X-RAY DIFFRACTOMETRY IN MATERIALS SCIENCE

Lev Zevin

Ben Gurion University of the Negev, Beer Sheva

Chemical compounds used as materials usually have an uncomplicated crystal structure

with a relatively small unit cell. It is the chemica! bond rather that any other factor that

determines the structure of the crystal and the class of material. The physical properties of

the material within a given class of compound, although related to the average structure,

are greatly influenced by deflections from the average structure or by crystal defects. The

mainframe of the crystal structure can be easily established from relatively nonprecise

diffraction data. Not so, for crystal defects, which produces only secondary effects in the

diffraction pattern, i.e., small variations in the position and shape of the diffraction peaks.

Thus, peak profiles themselves rather than their integrated intensities are often greater

interest to the materials scientist.

Nowadays we are witnessing a spectacular revival of interest in powder diffraction. The

reasons for this renaissance are many and varied, but the most significant single

development is the fitting of certain mathematical and physical models to the total

diffraction pattern. The elaboration of this technique has been facilitated by the

development of automatic diffractometers and the dramatic increase in the amount and

quality of the data that can be recorded in a given time. Achievements in modern

instrumentation and data processing are characterized by precision in peak location of

0.00 T and peak width of 0.05° for a well-crystallized material.

The following applications of modern X-ray diffractometry will be discussed:

Development of residual strains and lattice anisotropy in IVB metal nitrides

Residual strains and stresses in multiphase ceramics

X-ray diffraction by modulated structures and diffusion study

Refinement of crystal structures by powder diffraction data

Diffraction effects in metals produced by light atoms-hydrogen an helium

Anisotropic microstructural effects in materials

Full-pattern approach in phase quantification

J . 2 . 1

STUDY IN IMPROVEMENT OF WEAR BEHAVIOUR IN HIGH KINEMATICf PAIRS BY WAY OF A COMPUTER PROGRAM

E. Berman* and S.I. Griinfeld**

j *Depaitment of CAD/CAM/CAEJ

**Department of Mechanical Engineering, Ben Gurion University, Beer Sheva, Israel

The paper covers an improvement program related to wear behaviour in high kinematic

pairs. The program has been worked out based on adequate mathematic model, where

geometrical and mechanical factors of the kinematic pairs are taken into consideration.

The program allows for a tridimensional and bidimensional graphic representation of the

wear function, while making an estimation of possible critical zone. Although the

calculation is iterative, the number of iterations is relatively small, the method used being

the rapidly convergent method.

The paper gives numerical examples, which have also been experimentally checked.

3.2 .2

i

i ASPECTS OF BEHAVIOR CONCRETE MACHINE TOOL STRUCTURES USING

FINITE ELEMENT METHOD

Constantin Ispas, Constantin Dogariu, Aurelian Craciunescu

Polytechnic Institute of Bucharest, Romania

The recent machine tools must satisfy, to be competitive, specified accuracy of shape and

dimensions of the workpiece produced and it must show high technical performance with

economical efficiency. To answer at this need, the research workers by machine tools

field, searches to discover the new solutions, the new materials with remarkable

properties.

For machine tool structure elements, reinforced concrete simple and with resines was

adopted, to take the advantage of the experience and knowledge accumulated in civil

engineering and of inexpensive cost. Also, concrete has been used for machine tool

structures as a material which improves the damping of vibration characteristic.

The paper presents some aspects of behavior machine tool structures by reinforced

concrete in metallic shape. The finite element method is used to determine the

deformation state, the stress-slip values of a contact element describes of the interface

between concrete and reinforcement, the local stress state.

Material characteristic was determinated on the test bodies and on the material models.

Also, the drying process and this secondary phenomena, the concentration and slow

relaxation, was emphasized too.

The results obtained by finite element method was used to establish the best design for

machine tool structure elements.

3.2.3

*; A MODEL DESCRIBING THE CURVED ARRHENIUS PLOTS IN

SELF-DIFFUSION OF METALS

V. Segel*, J. Pelleg*, D. Fuks* and S. Dorfman**

*Department of Materials Engineering, Ben Gurion University of the Negev,Beer Sheva, Israel

**Department of Physics, Technion, Israel Institute of Technology, Haifa, Israel

The temperature dependence of the diffusion coefficient is discussed along the lines of a

model recently suggested, in which the total energy, Etot, per atom is concentration

dependent. The application of the model was tested by actual experimental data for a few

BCC and FCC metals. The basic assumption of the model are a) that the system of metal

and vacancies can be considered as random solid solution of holes in the bulk and b) the

formation energy of vacancies is concentration dependent. No other assumptions were

made in the model and no preconceived mechanisms for diffusion are postulated. The

usual Arrhenius equation

D = D o e x p [ - l / k T * ( E > E m ) ] (1)

has been modified to take into consideration the mentioned assumptions of the model and

it can be expressed as:

D = D o exp[- E° + E m + A/( 1 + exp (E°/kT ))) /kT] (2)

In the above equation D and Do are the diffusion coefficient and the preexponential factor,E v and Em are the migration and formation energies by a vacancy, and A, is a parameter

which is connected with the interactions of vacancies. The term modifying the usual

' Arrhenius relation is given according to the equation (A/(I + exp (E°/kT))). This term

takes into account the natural changes occurring in the vacancy concentration with

temperature.

The model was tested for FCC(Ni) and BCC(Nb, pTi, V). The choice of the metals was

aimed to test the universal application of eq. (2), since it is known that some of the metals,

"the so called anomalous BCC metals", show a strong temperature dependence beyond the

slight curvature found in some !•('(' metals also.

THE INFLUENCE OF SURFACE TREATMENTS OF ALUMINUM ALLOYS ONTHEIR RESISTANCE TO CORROSION FATIGUE

M. Landkof, J. Rezek, A. Cohen

The influence of surface treatments on the corrosion fatigue resistance of aluminum alloys

6061 and 50X3 has been investigated. The surface treatments included sulfuric acid

anodization and chromate conversion coating.

S-N curves of the two alloys, bare and surface treated, have been constructed both in air

and in 3.5% NaCl soln.

Chromate conversion coating improved the resistance of both alloys to corrosion fatigue.

Sulfuric acid anodization improved the resistance of AA5O83, but had a mixed effect on

AA606I, where in some cases it increased the susceptibility to corrosion fatigue. This

effect was attributed to the known susceptibility of the anodization layer to fatigue

cracking. AA5083 was found to be less resistant to corrosion fatigue than AA6061,

inspite of its well known corrosion resistance and its better fatigue resistance in air. The

susceptibility of this alloy was probably caused by hydrogen embrittlement.

3 . 'i . I

FORMICARYCORROSIONOFCOPPER :;

I. Weisshaus, A. Kaufman and E. Erdan

ORLIL Ltd. Night Vision Tubes & Equipment, Industrial Zone, P.O.Box 110,

Kazrin 12900, Israel

Pitting corrosion of copper and copper alloys was investigated intensively since the year

1950. There is an agreement about two types of pitting corrosion of copper as described

in the book of Szkalarska-SmiaJowska "Pitting Corrosion". :

Both types of corrosion refer to copper tubes used for water supply and in both cases the

corrosion mechanism is related to the water composition. The pitting causing water A

should be hard and contain high sulphate content and fairly low chloride content. Also, a ''

deposited carbon film is important for the creation of the pitting. According to Cornwell

copper without carbon deposit cannot reach the pitting potential.

Mattson assumed that in carbonate water with sulphate ions a basic copper sulphate forms

that enables the following reaction to occur: s

2Cu + H2O = Cu2O + 2H++ 2e-

All the above mentioned works and many other refer to the pitting of copper in water.

Only recently attention was paid to the type of pitting attack on copper where the species

causing the pitting are not the sulphate and the carbonate in the water. *

Copper tubes of heat exchanger units, suffer from a type of localized corrosion that

causes leaks in the tubes within a short period of up to three weeks.

A scanning electron microscopic examination of the corroded copper tubes surface and of

the cross section shows that the corrosion appears as pits that develop to a network of

microscopic grooves and caverens. The corrosion develops prefert ._,- along the grain

boundaries.

Analysis of the surface and the corrosion products by Auger electron spectroscopy detects y'

mainly three elements, namely, copper oxygen and carbon. In addition there are traces of \

sulphur and chlorine. £

The corrosive media was suspected to be L :riixture of organic acid (acetic acid) with |

humide air and water. The Handbook of Corrosion Data states that the copper and its f

alloys, except those with high zinc, show good resistance to all concentration of acetic fc

acid in the absence of oxygen or other oxidants. Contamination of the acid with air j

increases the attack significantly. I

The attack on the copper was repeated in the laboratory. | ' ' i

Specimens were immersed in a diluted and aerated solution of acetic acid. T[

I . I . ; .

II STRESS CORROSION CRACKING OF STAINLESS STEEL IN BROMIDE HEAVYI BRINESII P. Peled* and D. Itzhak**| *Bromine Compounds LTD. Israel

I **Materials Engineering Department, Ben Gurion University of the Negev, Israel

The stress corrosion cracking (SCC) of stainless steel in bromide heavy brine solutions,

was investigated. Susceptibility to SCC was exhibited in exposure to boiling ZnBr2, as

well as LiBr, at a temperature of 1450°C. Previous reports showed no SCC susceptibility

in exposure to NaBr, Zn/CaBr2 or CaBr2 heavy brines and some inhibiting effects of the

bromide addition in other environments.

3 . 3 . 3

THE EFFECT OF MELT TEMPERATURE ON THE ELECTRICAL RESISTIVITY

AND CRYSTALLIZATION TEMPERATURE OF AI91 - La5 - N14

AND AI91 - Ce5 - Ni 4 AMORPHOUS ALLOYS

V. Manov*, D. Shechtman*, A. Rubshtein** and A. Voronel**

•Department of Materials Engineering, Technion, Haifa, Israel

**Department of Physics, Tel Aviv University, Tel Aviv, Israel

New low density amorphous alloy ribbons with high Al concentration have been

produced by melt spinning in vacuum. The metallic alloys were melted in alumina

crucibles prior to their ra;id quenching onto a copper drum surface. Contact of the molten

alloys with the crucible and with residual gases in the vacuum was prevented by a layer of

molten salts.

Ductile rapidly solidified ribbons, the thickness of which is about 20 micrometers have

been prepared following different soaking times of the melt. Two series of experiments

were conducted. In the first, the molten alloy was soaked for 5 minutes at 1273, 1373

and 1473K. In the second, the alloys were soaked for 10 minutes at 1473K followed by

5 minutes at 1273 and 1373K.

The amorphous structure of all the ribbons has been confirmed by an X-ray diffraction

study. The specific electrical resistivity and its dependence on the preparation conditions

and on the alloy's temperature was studied over a large temperature range at heating rate

of 0.05 K/s. The electrical resistivity thus changes from 40 to 49 Ohmcm for

AI91- Las - Ni4 amorphous alloy ribbons and from 38 to 44 Ohmcm for different

samples of AI91 - Ces - Ni4 alloys. The variation of crystallization temperature and

activation energy of crystallization for the ribbons were determined.

3.3 .4

j USE OF ELECTRICAL EQUIVALENT CKCUITE TO SIMULATE SOME CASES OF

j PROTECTIVE COATINGS UNDER CORROSION CONDITIONS

£ Joseph Hazan and Joseph Yahalomi;

i Department of Materials Engineering, Technion, Israel Institute of Technology, IsraelIf In this work, the behaviour of (he interface under corroding conditions is simulated by

electrical equivalent circuits. The effect of the protection by anodizing, painting and

chromating is also described and discussed. In each case, attention is given in the

simulation, to the electrical parameters of the intact coating layer, to the porosity of the

protective film and to its evolution during the corrosion process.

Simulated results using various sets of parameter values according to experimental data

are reported and the most directly interesting quantities from the point of view of

corrosion, protection and diffusion are detected. Not all the electrical components related

to the different layers can be determined from the narrow experimental range of

frequency. The break points at very low and at very high frequencies in the log z vs. log

f Bode diagrams are not always detected in the case of anodized aluminium alloy (2024)

and the small capacitive loop at very high frequencies. In the case of a chromic-

phosphoric conversion later on zinc is not found in its entire form.

The influence of the separation of the time constants in the determination of the different

impedance parameters is emphasized.

Finally, the distortion of the impedance diagrams due to diffusion effects and to the

inhomogeneity of the surface are discussed.

3 . •> .

I SURFACE DIFFUSION AND COATING OF SiC AND B4C BY INTERACTION; WITH METAL POWDERSi

P. Mogilevsky*, 1. Gotman*, E.Y. Gutmanas* and W.A. Kaysser**

•' *Department of Material Engineering, Technion, Haifa, Israel

**Max-Planck-Institut, Stuttpart, Germany

SiC and B4C are known to react with metals at high processing or service temperatures.

This interaction has a detrimental effect on the properties of metal matrix composite

materials reinforced by SiC and B4C fibers or whiskers. Controlled reactions, and

especially those accomplished before the final processing, may be helpful in protecting the

ceramic/metal interface from further degradation. In the present work, the interaction of

SiC and B4C ceramics with Cr and Ti powders was investigated. Experiments were

performed on SiC or B4C plates immersed into the metal powders. Partially immersed

samples were used for investigation of the surface diffusion of the metal atoms on a

ceramic surface. It has been shown that SiC and B4C can be successfully coated by

interaction with Cr and Ti powders. During vacuum heat treatments at 1173-

1473°K,reactive diffusion of metals atoms along the ceramic resulted in the formation of

coatings OP the ceramic surface. The microstructure and phase composition of the

coatings obtained were studied employing X-ray diffraction, SEM/EDS and Auger

spectroscopy. The coatings have a multi-layer structure, the phase composition of the

interfacial layer depending on the thermodynamics of the corresponding ceramic/metal

system. The coatings formed on the SiC surface were found to contain carbides and

silicides of the corresponding metal, the outer layer being a carbide or a mixture of a

carbide and a silicide. Treating B4C in Cr powder yielded a coating which consisted of Cr

borides and amorphous carbon, the outer layer containing only the borides. This coating

growth was shown to be controlled by diffusion.

Thermal stability of the coated and uncoated ceramic/metal interfaces was estimated by

placing SiC and B4C plates into Fe- and Ni-base matrices and annealing the obtained

model composites at 1273-1473°K for 1-10 h. The coatings obtained by treating SiC in

Cr and Ti powders have been found to considerably improve the thermal stability of SiC

in Fe and Ni matrices. A preliminary study of the thermal stability of B4C in a Fe matrix

has shown that the coating of this ceramic by interaction with metal powders may be

effective in preventing chemical interaction at Bimetal matrix interfaces.

i.A.l

ELECTROPHORETIC DEPOSFTION OF HYDROXYAPATICE COATINGS FOR

MEDICAL APPLICATIONS

A. Zhitomirsky, L. Gal-Or

Institute of Metals, Technion, Haifa, Israel

In the last few years many studies have been proven that hydroxyapatite (HAp) hasexcellent biocompatibility as its chemical composition is identical to that of bone tissue.Clinical observations have shown that when HAp is implanted in bone, a tight bondbetween the bone and the implant develops. Unfortunately, HAp has a low tensilestrength and its resistance to fatigue failure is also vc.y low. In order to overcome thesedrawbacks co;<ted metal and composite implants are under extensive investigation.

HAp coated Ti implants are currently of much interest. Coatings are found to providegood biocompatibility, ability of bonding to bone, enhacement of new bone formation andcorrosion protection of the metallic substrate. HAp ceramic fibers are of a high potentialfor development of composites. Considerable attention has been given to develop low-cost method for manufacturing continuous, uniform, fine grained fibers. Problems ofstoiciometry, sinterability, formation rate and thickness control are also of great practicalsignificance,

It is the aim of this study to develop HAp coatings on titanium alloy implants and HApfibers by electrophoresis.

The HAp precipitaion experiments were performed at variable experimental conditions.Powders of varying degrees of crystallinity and thermal stability were synthesized,studied and used for electrophoretic deposition.

In order to prevent compositional changes of the coating during the sintering stage, anodicoxidation of the substrate was performed for development of protective layers on theTiAlV alloy specimens. The obtained oxide films are found to contain phosphorus inaddition to the alloying elements as well as oxygen. Carbon fibers of 7 |im diameter wereused a a template for HAp fibers development.

In contrast to results of some previous works submicron HAp powders were successfullydeposited on the Ti alloy specimens and carbon fibers. The developed technology of fineHAp powder preparatoin allows to obtain relatively high deposition rates at low currentdensities. Variation of deposit weight with time and applied voltage were studied andi/nalyzed.

Sintering behaviour of HAp coatings was studied at temperatures below the transitionpoint of a + p -> P in the Ti Al V substrate. It has been established that low temperaturedensification is a result of the use of submicron particles. In our work the problem ofcoating densification has been also approached by use of cementitious bonding. Atechnology has been developed for preparation of hollow HAp ceramic fibers. Thistechnology allows the simple solution of some technological problems in this field.

3.4.2

MICROSTRUCTURE, PHASE COMPOSITION AND RESIDUAL STRESSES IN

PLASMA SPRAYED THERMAL BARRIER COATINGS

M. Levit, S. Berger and B.Z. Weiss

Department of Materials Engineering, Technion City, Haifa 32000, Israel

The development of the thermal barrier coatings (TBCs) has received a great deal of

attention in recent years. The present investigation was conducted on a duplex system

consisting of a ZxQz-1 V2O3 outer ceramic layer over a NiCrAl Y inner metallic bond coat

layer. The state of residual stresses, bonding mechanisms, microstructure, phase

composition, interface phenomena, ir teri jnellar contact and internal lamellae structure of

thermal barrier coatings were studied. The coatings were deposited by atmospheric plasma

spraying on a Ni-based alloy substrates, which were kept at different temperatures during

deposition.

The research was carried out by using Transmission and Scanning Electron Microscopies

combined with Energy Dispersive X-ray Spectroscopy, Optical Microscopy and X-ray

Diffraction.

It was found that both the plasma-sprayed bond and the ceramic coatings have a

characteristic lamellar microstructure. The bond lamellar is composed of an outer

amorphous film of oxides, an intermediate thin layer of columnar oxides grains and an

inner polycrystalline region consisting of elongated intermetallic grains. The ceramic

lamella is composed of an outer amorphous film and an inner region of columnar and

equiaxed grains of the metastable tetragonal t-ZrO2 phase. Increasing the substrate

temperature from 75°C to 500°C has not a significant influence on the microstructure, but

the state of residual stresses in outer ceramic layer changes from tension to compression.

The effect of the substrate temperature on the microstructure, composition and morphology

of the interfaces, and on the residual stresses in the ceramic layer will be discussed.

A mathematical model predicting the temperature and the velocity of the ceramic and

metallic powder particles during the plasma spraying and before impact to the substrate

was developed. The analytically calculated data have shown a good agreement with

experimental results.

1.4.1

I PRODUCTION OF Cr BASED COMPOSITE COATINGS IN THE PRESENCE OF

§ ADDITIVES

j 0. Berkh, S. Eskin, J. Zahavi

i The effect of additives on particle codeposition with a chromium matrix is considered. It

is shown that surface active additives act as particle codeposition stimulators or influence

the morphology and phase composition of the matrix. Codeposition stimulators can either

reduce electrolyte surface tension or be adsorbed on the surface of the cathode and

particles changing the particle surface charge and adsorptivity. Additives involving matrix

phase transformation can improve hardness and wear resistance of the composite coating

and thus intensify the positive effect of the incorporated particles.

Saccharin effect on AI2O3 particle codeposition with Cr-and Cr-Ni alloy from electrolyte

on N, N-dimethylformamide base has been investigated. Saccharin introduction into

electrolyte does not increase amount of AI2O3 particles in composite Cr-Ni coating but

reduces coating deposition rate, internal stresses and wear of deposits.

In order to reveal the role of saccharin in AI2O3 particle codeposition with Cr-Ni alloy,

cathodic polarization measurements during codeposition process also spectral tests of

electrolytes and partical electrophoretic mobility examination were carried out. On the

base of obtained data mechanism of saccharin action is discussed and recommendations

for CrMi-Al2O3 composite production are proposed.

3 . 4 . 4

DIAMOND COATINGS

Z. Klein, A. Markovitch, A. Shalmon

? Dept. 27, Rafael, POB 2250, Haifa 31021, Israel

I Hot filament and microwave plasma assisted CVD processes have been used to produce

diamond coatings.

Thin diamond films of 1-40 |im have been deposited on silicon substrates up to 25 mm

diameter, at deposition rates to three microns per hour.

A free standing diamond film, 40 \im thick was obtained by etching the silicon substrate.

Influence of several process parameters on the deposition rate and on the quality of the

diamond films was investigated.

* filament materials and shapes

* filament and substrate temperature

* distance filament - substrate

* MW power

* substrate preparation

* Composition concentration and flow rates of gases

Characterization of the diamond films was done by Scanning Electron Microscopy,

Raman and Infrared Spectroscopy.

3.4.5

ft

iMECHANOCHEMICAL METHODS IN MATERIAL SCIENCE

PJu. ButyaginInstitute of Chemical PhysicsRussian Academy of Science

Kosygina Str. 4, V-334Moscow, 117977 Russia

The oldest mcchanochemical process is the production of the fire during friction ofwood sticks. By the friction the cellulose macromolecules are ruptured and freeradicals are formed. Free radicals initiated chain oxidation of cellulose. Thereaction of oxidation accompanied by heating. The heating leads to combustion.

The next old mcchanochemical technology is the plastication of rubber. More recenttechnology is the preparation of superhard materials by the mechanical treatment ofinitial elements mixture. The example of mechanochemical processes in materialscience are surface modification, activation of sintering, low temperature synthesisand alloying, soft methods of material testing and many others.

In the base of all above listed efforts lies the following fundamental phenomenon. Inthe course of mechanical action on solids the elastic energy not immediatelytransformed into Joule heat. Between action and heating there exists therefore asequence of the nonequilibrium intermediate states:

MECHANICAL WORK - - - - • ELASTIC ENERGY

STRUCTURE H.ECTRONICALLY VIBRAT1ONAL TRANSLATIONDEFECTS EXCITED STATES EXCITED STATES MOBILITY

JOULE HEAT AND STABLE DEFECTS *

Every intermediate state can be characterized by the energy yield, life time andchemical reactivity. For a lot of systems the nature of these states are determined.The mechanical activation consist in the production of structure defects. Mechanicaldefects accelerate the sintering and other diffusion controlled processes,dissolving,chemical and physico-chemical transformations, in (he limiting case the mechanicalactivation leads to amorphous state. It is a way to the production of materials withnews property.

The modification of surfaces is the result of mechanical treatments of powders inchemical active media (gases, liquid). The fracture and friction of particles bytreatment lead to surface disordering. On the surface arise low coordinate atoms,free radicals, deformed interatomic bonds, electron exited states. All thesechemical active structures decay as a rule in the course of physical relaxation andreaction with oxygen or other gases. But it is also possible to involve "11 theshort living active centers and exited states in useful chemical transformation. Insuch a way one can prepare highly disperse powder for composite materials.

The last group of processes based on the effect of translation mobility by plasticdeformation. The deformation mobility on atomic level were simulated by themolecular dynamic method. The attention to this effect is connected with thesynthesis of the materials in solid phase without dissolving, heating or melting themixture of reagents. If the products of inechaaoehemical synthesis were formed incold regime they have disordered nanocrystalline or amorphous structure.

1 . 1 . 1

I RESIDUAL MECHANICAL PROPERTIES OF ABLATIVE COMPOSITES ON

| EXPOSURE TO HIGH TEMPERATURES

t\ Haya Weisshaus, Israel Engelberg* ADA, P.O.Box 2250, Haifa 31021

Ablative composite materials exposed to high temperatures are subjected to two types of

changes. The first is a chemical change of the polymeric matrix while pyrolysed. The

second is composed of all the physical changes in matrix dimensions and the

reinforcement's relative location within it. Erosion is an additional change caused when

the source of heating is exhaust gases of rocket motor engines.

These changes result in degradation of the initial mechanical properties of the composite.

Ablative components are designed considering this degradation and calculations even

maximize it by diminishing values to zero as a safety factor. However, the price in extra-

load is especially expensive in avionic components.

This study was aimed to measure the residual mechanical properties of the ablative

composites at the actual high temperatures of application, as related to these temp, and to

factors of their composition and fabrication. Connecting the information with the erosion

behavior will enable implementation of results in practical calculations, improving the

component's design.

The relationship between temp, and pyrolysis mechanisms is quite known for Phenolic

resin, the most abundant matrix. It is also believed that the heating rate and exposure

duration as well as its combination with thermal conductivity at the specified temp., has a

significant influence on the residual mechanical properties.

Shape and dimensions of the specimen become therefore relevant parameters. In addition

to these it is expected that the composition of the raw material, its manufacturing and

polymerization processes will affect the residual mechanical properties.

This study began with a carbon/phenolic ablative composite. It is a rayon precursor

carbon fiber, satin weaved reinforced composite. Two procedures were chosen to

fabricate plates of specified thickness, from which samples were cut out. Sizes were in

4 . 1 . 2

ji STRESS AND FAILURE ANALYSIS OF TAPERED ADHESIVE JOINTSif

§ A. Buchman, F. Weinstein, Y. Holdengraber, I. Honigman and H. Dodiuk

% RAFAEL, P.O.Box 2250, Haifa 31021, Israel>,I Advanced thermoplastic composites have been recently introduced to the aerospace and

I military market. As consequence the joining ol thermoplastic composites have become a

critical manufacturing step. Due to geometrical imperfections and production processes of

a layered composite with bonded joints a tapered adhesive is sometimes formed instead of

a parallel one which leads to a loss of structural stress.

A correlation between numerical results obtained by the Finite Element (F.E.) method and

experimental data for parallel compared to tapered butt joints under tensile load was

studied.

The experimental results were obtained with two kinds of adherents (metallic and plastic)

and two adhesives (flexible and brittle) for various adhesive layer thicknesses and taper

angles.

Two linear finite element simulations were constructed for both joints. The numerical

results were used for modelling the ultimate tensile strength values and the failure modes

for the various thicknesses of the adhesive joints tested.

The numerical and test data results have shown that a thinner parallel adhesive layer leads

to a stronger joint. An optimum adhesive layer thickness was found for the tapered

configuration (0.4-0.5 mm). This thickness was achieved when the stress value and its

gradient were distributed in an optimal ratio. Then, the mode of failure was changed from

adhesive (interfacial) to cohesive (in the adhesive).

The enhanced sensitivity found for the tapered joint strength as a function of its thickness

leads to the conclusion that in composite layered bonded structures such joint should be

prevented. Thus parallel joints in addition to other important parameters (surface

treatment and material properties) should be considered.

4 . 1 . 3

FATIGUE MECHANISMS OF 95 / 5 Pb / Sn MICRO SOLDER JOINTS UNDER

FULLY REVERSED SHEAR

Nahum Nir*. Arthur R. Storm*1", T.D. Dudderar**

*AT&T Bell Laboratories, Murray Hill, NJ., U.S.A.

**Rafael, POB 2250, Haifa 31021, Israel

In this study SEM Failure Mode Analysis (FMA) has been used to develop a new

understanding of the mechanisms of Low-Cycle Fatigue (LCF) in 95/5 Pb/Sn solder

micro-joints typical of those being used in high density micro-electronics. As a result it is

now understood that many of the same phenomena that come into play in the LCF of high

performance structural alloys play the same roles in solder micro-joints. However, it is

necessary to also consider the added dimension of a relatively large (compared to the

micro-joint volume) grain size which under all conditions makes microstructure (1) an

important factor in determining the effective mix of active fatigue damage mechanisms

and, under certain (relatively common) conditions of micro-joint geometry, (2) a major

factor in determining the resulting fracture surface morphology. These understandings

support the development of rational methodology for the optimization of flip-chip

assembly processes, the selection of appropriate pad metallizations and the refinement of

solder alloys for improved micro-joint reliability.

4 .1 .4

J

FRACTURE TOUGHNESS MEASUREMENTS FOR CERAMIC MATERIALS

A. Ashur, A. Cohen

Rafael, M.O.D. Hifa, Israel

Fracture toughness testing has recently gained importance in ceramic materials

characterisation.

There are several methods of testing fracture toughness in ceramic materials but there is

no standard method for KJC measurement.

The fracture toughness values in ceramic materials depend on production process,

microstructure, specimen geometry and the specimens preparation technique.

In this work we have tested two different materials: ZnS and Slip Cast Fused Silica

(SCFS), and compared the relative merits of the following testing methods: Single edge

notch beam (SENB) Chevron notch. Indentation crack length and Indentation strength.

The ZnS had been produced by CVD process. The material had no faults such as

microcraks, porosity, etc. The Kic values, as measured by Chevron notch and by SENB

methods were very similar, but different values were obtained by Indentation Strength

method and by Indentation crack length methods.

For SCFS material there was a considerable difference between the SENB and Chevron

Notch KJC results. The scatter was similar for both methods.

Indentation crack length and Indentation strength methods were inaplicable in this case,

since the material is porosive.

In the Chevron notch method, the crack geometry changes during its propagation.

Consequently the influence of the specimen geometry on measured Kic values is reduced.

4 . ! . 5

THE EFFECT OF IMPURITIES ON THE TENSILE ELONGATIONOF BERYLLIUM

O. YeheskelNuclear Research Center-Negev, P.O. Box 9001, Beer Sheva, Israel

From literature survey the effects of beryllium oxide content and the content of

impurities like iron, aluminum, silicon and magnesium , on the room temperature

tensile elongation of beryllium were studied. The data from the literature is

related only to beryllium which was processed by the powder route. No indication

exists to a single metallic impurity which affects tensile elongation. The known

relation ' that the tensile elongation is reduced with the increase of beryllium

oxide content is found, but linear regression shows large spread. The effect of

ratios of different impurity contexts on tensile elongation are examined as well. It

is found that when Be() content is multiplied by the molar to atomic ratio of BeO/Si

linear relationship with elongation exists. From linear regression the relationship

between the tensile elongation, e, and the BeO content molar to atomic ratio is:

e(%) = 4.02 - 5.3'10'3 • (wt%)BeO* (mol%) BeO/ (At ppm) Si.

The ./egression coefficient r = 0.79, Similar relationship with shallower constant

and larger spread is found in these specimens tor the Al content multiplied by the

molar to atomic ratio BeO/Al. The atomic ratio Fe/Al, which is correlated to the

phase FeAlBe, shows no relationship to the tensile elongation, indicating that this

phase, has no crjeial effect on tensile elongation at room temperature as opposed to

elongation at high temperatures ' . It is found that for specimens which underwent

HIP consolidation , maximum elongation of about 4.5% is reached al the grain size

range of (>-9u,m. It is shown in the present work that grain growth in beryllium thai

is processed in the powder route ' , can be correlated with the molar to atomic

ratio BeO/Si. It is postulated that the presence of silicious phases at the grain

boundaries enables the annihilation of dislocations which are generated at Che BeO/Be

interface due to the thermoplastic stresses during the cooling from processing

temperature. The reduction of dislocation density contribute to the increase of

tensile elongation. The possibility of slight grain boundary sliding in beryllium al

room temperature is discussed. Ways of increasing the tensile elongation of

beryllium al room temperature are given.

. Z . ]

\ THE PREPARATION OF FIBER REINFORCED ALUMINIUM SiCr/ 6061 BY

| DIFFUSION BONDING

f M. Paz, J, Mironi, N, Atzmon, M. Elkaiyam

I Two processes for the preparation of Silicon Carbide fibers - reinforced aluminium - Hot

j1 Pressing (HP) and Hot Isostatic Pressing (HIP) - were examined. Various basicL- configurations - plane, cylindrical and "channel like" - were produced and characterized.

The effect of the parameters on the mechanical properties of the configurations were

studied.

The basic configurations produced and characterized were variously combined in order to

ascertain the possibility of their further employment.

.2

COMPARATIVE STUDIES CONCERNING THE BEHAVIOR OF RESIN / FIBRE

GLASS COMPOSITE MATERIAL

Ispas Constantin*, Gramada Dan**

•Polytechnic Institute of Bucharest, Romania

**S.C. SIMTEX S.A., Romania

One of the major directions in technological enhancement consists in investigations to

obtain durable, light-weighted, various, resistant, easy machinable materials, and which

should simultaneously cover more specific requirements. Composite materials (CM),

which accomplish the majority of these conditions, have known in the last years an

explosive multiplication of their fields of application.

One of them-machine constructions, and more particularly machine-tools accomplishment

- have been an interesting area for extending the use of composite materials. In this spirit,

in Romania there have been developed studies and searches for improving the behavior of

the machine-tools in the cutting process and to elaborate new types of composite

structures.

A step in this searches consisted in comparative studies on the behavior of various

samples of CM in different conditions. There have been selected for experiments samples

of CM with matrix of unsaturated polyester resin with medium viscosity and fast

polymerization, reinforced with four kinds of fibre-glass type E. All the working

materials are in the current production of specialized firms in Romania. The samples were

produced by the direct manual forming process.

On specific testing stands, there have been experimented the behavior of samples on

static, dynamic and tribological (the response at wear and tear stress and defining the

friction coefficient) applications. In the paper are comparatively presented the results

obtained during the experiments accomplished on the presented CM and some other

plastic and metallic (ferrous ans non-ferrous) materials, currently used in machine-tool

building.

The results permitted the elaboration of some recommendations regarding the optimum

intimate structure of CM resin/glass in the specific applications in machine-tool building.

A . ? . i

RECRYSTALLIZATION OF TUNGSTEN BASE HEAVY METAL ALLOYS

Chaim Weinberger and Dov Chaiat

TAAS - Israel Industries Ltd.

The traditional-tungsten base heavy-metal alloy is a composite material, containing a

minimum of 8.5wt% of tungsten grains embedded within a W-Ni-Fe matrix. Liquid

phase sintering of this two-phase alloy results in spherical tungsten grains, with an

average grain size of 30± 10 micrometers.

Rotary swaging is a well-known technology used as part of a thermomechanica) heat

treatment in tungsten alloys. Tungsten-base alloy bars are usually swaged up to a

maximum 30% reduction in area. The swaging results in a slight deformation of the

tungsten grains.

Several recrystallization heat treatments were performed at temperatures of 1430 and

1500°C in order to determine recrystallization behavior with various amounts of cold

working of the two types of alloys: A-90 and A-95.

4 .2 .4

LASER SURFACE ALLOYING OF FERROUS ALLOYS WITH CrB2:

SOLIDIFICATION BEHAVIOR AND MICRO • STRUCTURE

G. Shafirstien*, S. Ariely**, M. Bamberger*, F. Maisenhalder** and M. Langohr**

*Department of Materials Engineering, Technion, Haifa, Israel

**DLR Stuttgart, Germany

A CW-CO2 laser was used to alloy the surface of a-Fe and AISI 1045 steel plates with

CrB2 by the powder injection method. The OB2 particles were partially dissolved in the

bath forming a melted layer of Fe-Cr-B or Fe-Cr-B-C its thickness and B content depends

on the laser parameters and the substrate's thermo-physical properties.

The typical microstructures were: 1) Columnar iron-borides which grow on the residual

chromium borides, 2) Iron dendrites which grow on the substrate, 3) Eutectic and 4) a

layer of iron borides which engulfs the OB2 particles. The solidification behavior

resulting the co-existence of these phases and its dependence on the laser operating

parameters will be discussed based on a simplified mathematical model.

4 . : ' . " '

ULTRASONICS AS A RESEARCH TOOL

IN POWDER TECHNOLOGY

O. YeheskeJ, H. Klimker, Y. Gefen, M. Ganor

Physics Division

Nuclear Research Center - Negev

P.O. Box 9001, 84190 Beer Sheva, Israel

When an ultrasonic sound wave is travelling through powder particles pressed

together, its velocity is affected by the nature of the phases comprising it, the

quality of the bom! between the particles and the volume of pores. The longitudinal

and transverse sound velocities thus realized, are related to the elastic moduli of

that bulk. This is the theory underlying the foundation to the possibility of

measuring the clastic properties of powder compacts as they are being densifled via a

I'owder Metallurgy (P/M) route.

Examples of sound wave velocity measurements on post sintered metals and ceramics

specimens and during Hot Isostatic Pressing (HIP) of powder specimens are shown.

Changes in sound velocity during densificalion are related to various stages of the

sintering processes while they occur. A measure to the material quality can thus be

set. The technique was successfully applied to study the effects of the HIP cycle

parameters e.g., temperature, pressure and time, on the dcnsificalion mechanisms in

l-e, NaCl and Ti Al.

The agreement of relevant theories to experimental data will be reviewed.

4.

EFFECT OF PROCESSING ON MICROSTRUCTURE AND PROPERTIES OFTUNGSTEN HEAVY ALLOYS

E.Y. Gutman, D. Zack and D. Chalat

Department of Materials Engineering, Technion, Haifa, Israel.

The effect of high energy attrition milling, high pressure consolidation and of alloying on

niicrostructure and mechanical properties of tungsten heavy alloys was investigated.

High level of homogeneity was achieved by attrition milling of the powder blends.

Alloying elements enhancing diffusion and high pressure consolidation lower the

temperature or shorten the exposures at temperatures which provide full density. All this

provides retention of fine scale microstructure resulting in higher yield stress and

hardness of the alloys.

4 . 3 . 2

STRUCTURAL CHARACTERIZATION OF EPITAXIAL THIN FILMS

BY RECIPROCAL SPACE MAPPING

Gerardo H.O. Daalderop, Tom R. Ryan

Philips Analytical X-Ray

Almelo, The Netherlands

By use of X-ray diffraction a wealth of information about the structural properties

of materials can be obtained. In this contribution we will specifically focus on the

use of reciprocal space mapping to characterize epitaxial thin films. The

distribution of X-ray intensity around the reciprocal lattice points can give direct

evidence of the presence of pseudo-morphio coherent, relaxed incoherent, tilled

growth, sub-grain boundaries or sample curvature. To achieve this, it is essential

that the integration volume in reciprocal space, determined by the resolution of the

optics of the diffraclometer, is less than the width of the X-ray intensive in

reciprocal space.

In this contribution, the concepts will be introduced briefly, followed by examples

dealing with 111-V coherent layers, II-VI incoherently grown layers, HTo

superconductors and magnetic metallic multilayers. The advantages are shown of

matching the optics to the materials problem. This work was done with the Philips

Materials Research Diffractometer where the optics can be changed within seconds. We

demonstrate how this interrhangeability is crucial for the analysis of a wide range

of slructural problems.

4 . i .

MICROSTRUCTURE OF Al-U ALLOYS SOLIDIFIED AT COOLING RATES

BETWEEN 0.03^.5 K/SEC

A. Munitz, V.Y. Zenou, C. Cotler, A. Zahavi, and Z Barkai

Nuclear Research Center-Negev, POB 9001, Beer Sheva, Israel

High purity aluminum (99.99%) and high purity uranium (99.9%) were used to prepare

Al-U alloys with U concentration ranging between 15-27 wt.%. Alloys with the desired

composition were melted in a resistance furnace in an alumina-coated graphite crucible

under argon atmosphere. The microstructure was examined utilizing scanning electron

microscopy with EDS capabilities. The eutectic composition was found to be an

increasing function of the cooling rates. The results are discussed in term of existing

solidification theories.

U:4 . 4 . 4

IMPROVING PRODUCT DESIGN THROUGHA CONTROLLED EXPERIMENT

Benny Milman*, Issachar Sirota*, David M. Steinberg**

*TAAS Israel Industries, POB 1044, Ramat Hasharon 47100, Israel

**Tel Aviv University, Ramat Aviv 69978, Israel

One of the important goals of quality management in today's competitive marketplace is to

build quality into products and processes at the development stage. The use of

statistically controlled experiments, in which several parameters are studied

simultaneously, can help accomplish this goal efficiently. This paper describes a case

study that illustrates the utility of controlled experiments in product development. The

customer required improvements in the safety of a pyrotechnic ignitor used in one of the

products they purchased. The safety improvements could be met by replacing the "match-

head" initiator by a type 1A/1W no fire initiator. However, there was concern that

changing the initiator might degrade other important product performance characteristics.

A controlled experiment was designed to compare three different initiators, the booster

charge and the main charge. The experiment quickly and efficiently pointed to a superior

initiator and the optical charges to maintain high performance with enhanced product

safety.

COMPUTERIZED SYSTEM FOR EVALUATION OF ENERGY ABSORPTION

DURING LASER TREATMENT OF METALS

Dr. M. Geller, Dr. E. Armon and Prof. M. Bamberger

Department of Materials Engineering, Technion, Haifa, Israel

Knowledge of the interaction of a workpiece and laser radiation is of extreme importance

in application of laser technology to materials processing. At present, only relatively few

publications contain relevant quantitative data.

In the present work a new method was developed for determination of the energy

absorbed by the substrate during laser irradiation. This was done by solving the "Inverse

Problem of Heat Conductance" for the treated metal with a view to determining the

temperature-time pattern in the substrate, which in turn yielded the heat flow into the

workpiece and the temperature of the treated surface. By this means the coupling between

laser radiation and matter was quantitatively described, as function of the surface

temperature. The resulting equation was used in a simulation algorithm for the laser

surface heating, which finally yielded the thickness of the treated layer as function of the

laser operating parameters. The calculated and measured values are in quite good

agreement.

I

I

/ •

4 . 4 . 1

THE INTERFACE FORMED BETWEEN PbBiSrCaCuO HKiH-TcSUPERCONDUCTOR CERAMIC AND Ag OR Ag-BASED ALLOYS

N. Froumin, J. Baram and M. Polak

Department of Materials Engineering, Ben Gurion University, Beer Sheva, Israel

Properties of interface formed between high Tc superconducting materials and metals are

of a great importance due to their effects on the performance of practical devices. We

have studied the interactions between PbBiSrCaCuO and silver: 1) deposited as a thin film

subjected to 3()0-7()0°C heat treatments, and 2) as the metallic melts in wetting sessile

drop experiments. The interface chemistry of the deposited film was examined by X-ray

Photoelectron Spectroscopy (XPS), combined with argon sputtering. Elemental diffusion

into the silver overlayer with significant temperature-dependent segregation of bismuth at

the silver surface. The contact angle obtained in the wettability experiments for silver melt

on PbBiSrCaCuO was 78 degrees with improved wetting effects in the following alloys:

Ag-4%Bi, Ag-4%Pb and Ag-4%Cu. Both EDAX analysis of the drop/ceramic interface

and AES analysis of the drop surface and periphery indicate dissolution of the ceramic

elements in silver, segregation of the bismuth on the top surface of the drop and fonnation

of an interaction zone at the drop periphery, containing silver, less copper, more bismuth

and calcium than in the ceramic. Furthermore, there is evidence for the presence of some

silver on the free ceramic surface. Correlation is made between these XPS results with

reported results on contact resistivity in the system BiSrCaCuO/Ag films. The wettability

results of PbBiSrCaCuO ceramic by liquid silver or silver alloys can be used for

optimization of adhesion in the composite materials, and therefore eventually enhance

electrical properties.

4 . -'I.. ' '

DEPOSITION OF DIAMOND-LIKE CARBON FILMS BY LASER PLASMA TECHNIQUE

J. Karpman, M. Riabkina-Fishman, J. Zahavi

Israel Institute of Metals, Technion.

Diamond-like carbon films (DLC) were prepared by 193 nm, 25 ns pulse duration,

2-10 Hz frequency, ArF excimer laser ablation of a high purity graphite target.

Laser-plasma enhancement by means of special electrode, near the target and substrate

and bias was also used. The effects of substrate temperature, laser flux and in situ laser

pretreatment of the substrate surface on the optical, mechanical properties and electrical

resistivity of the films were investigated. Film thicknesses were 40-1200 nm, substrate

temperature ranged from room level up to 250°C; laser fluxes -107 -5 • l() l l ) W/cm2.

SEM, Ellipsomsometry, X-ray analysis, Auger and Raman spectroscopy, IR

transmittance, were used for coating characterization. Adhesion of films to substrates

was measured by scratch testing and by a method based on measurement of the tear

effort. We deposited amorphous, smooth, hard films with good adhesion. It was found

out that as laser flux density increases, the amount of particles, knocked out of the target,

also considerably increases. Electrical discharge generated by the laser plume also

enhances this trend. Laser-induced plasma appreciably (as much as 3-5 tiines) increases

the deposit growth rate owing to additional etching of the target. Adhesion and hardness

of films increase steeply as substrate temperature and laser flux density rise.

Laser-induced plasma has little effect on adhesion properties but increases film hardness.

Pretreatment of the substrate by diamond paste does not affect growth rale, film

morphology and does not substantially improve adhesion strength at the low substrate

temperature. IR measurements show considerably transmittance throughout the whole

range of 400-4000 cnr ' .

4 . 4 . i

RECONSTRUCTION OF SURFACE AND ENVIRONMENTAL SENSITIVE

MECHANICAL BEHAVIOR OF METALS

E.E.Glickman

Graduate School of Appl. Sci. and Technol., the Hebrew University, 91904, Jerusalem

Sufficient reduction in specific surface energy resulted from adsorption, wetting and

electrical charging is often assumed to play a decisive role in environment induced

degradation of mechanical properties of solids (Rehbinder-Westwood effects of

plasticity).

But neither surface energy-mechanical properties relations nor a mechanisms which may

be responsible for such a relation are well established.

The present paper offers a brief review of Surface Energy Effects in Metal Plasticity

(SEEMP). A special emphasis was made on the recent direct observations of kinetics of

subcritical crack growth and voiding, grain boundary sliding and creep in simple model

systems under controllable decrease in specific surface energy. Relevant fractographic

and acoustic emission finding are also discussed.

Proceeding from these data we suggested a microscopic mechanism of SEEMP whose

basic concepts may be formulated as follows:

(i) SEEMP results from an acceleration of diffusion mass transfer in a near-surface

region;

(ii) an essential reduction in a specific surface energy y (for example from wetting of a

solid metal by a liquid one) leads to an essential decrease in the formation energy

Uk ^ y of kinks (semicrystalline positions) located at surface ledges and of vacant

sites at smooth terraces;

(iii) thus, transition from atomically smooth to atomically rough surface which consists

in a drastic increase in thermal equilibrium concentration of these defectsQ »= exp -yAT may well take place;

(iv) this in its turn increases the efficiency of the surface as source and sink of point

defect involved into diffusion controlled processes of creep, voiding and subcritical

crack growth in the vicinity of the surface.

Exponential relations "specific surface energy y-crack velocity (rale of voiding) creep rate"

observed on experiments in near-surface region give a good evidence in support of the

suggested mechanism of SEEMP.

The results are of interest for understanding one of the basic mechanism of environmental

sensitive mechanical behavior of metals.

4 . 4 . 4

THE NKW METHOD OF CRYSTAL PERFECTION CHARACTERIZATION USING

X-RAY BRAGG REFLECTIONS

Yuri Rosenberg

School of Physics and Astronomy, Tel Aviv University, Tel Aviv, Israel

A knowledge of the degree of the crystal perfection is of fundamental interest for appliedresearch where these crystals are used. X-ray diffraction on the strength of its nature isone of the most appropriate methods for crystal lattice imperfections study. One of thewidely used approaches in this field is based on the comparison of experimentallymeasured integrated intensities Int (hkl) of X-ray Bragg reflections (hkl) with the resultsof calculations by some theoretical model of structure defectivness. As is generallyknown for any crystal the experimentally measured value Int (hkl) for every reflectiondoes lie in the range with well-specified limits. The lower limit Dyn (hkl) corresponds toideally perfect crystal, the upper one Kin (hkl) - to ideally mosaic crystal, theproportion Kin (hkl) / Dyn (hkl) depends on the structure factor of considered reflectionand X-ray wavelength used and may be as high as 100.

The theoretical description of X-ray diffraction in perfect and slightly distored crystals -dynamical theory is highly reliable as well as the kinematical theory, describing the X-rayscattering from ideally mosaic crystals. Nevertheless a great majority of crystals areneither perfect nor ideally mosaic. Until now for them there are no other way except forapplication of the kinematical theory with extinction correction. But this approach isreally adequate only for crystals where the Int (hkl) of the most strong Bragg reflectionsare not less than 80-90% of Kin (hkl). However the integrated intensities of a lot ofpractically important crystals are essentially smaller than Kin, often in these crystalsInt(hkl)/Dyn (hkl) is not more than 3-5 and correspondingly, Int (hkl) / Kin (hkl) is lessthan 0.1 -0.3. The goal of the present work was to characterized the structure perfectionof this kind of crystals.

For ihe interpretation of experimental intensities obtained in symmetrical Bragg case wasto modify the standard dynamical theory formulas as follows:

Int (hkl) = | Dyn (hkl) / P] * [R* /R], R1 = R(g / P),

where Dyn (hkl), R and g are computed after W.H. Zachariasen ("Theory of X-raydiffraction in crystals", N.Y., Wiley, 1945), and P - empiric parameter, being

= {l=[S(hkl)/D]2j-0.S

where S (hkl) - the extinction length and D - mean coherence domain dimension in <hkJ>direction.

On a double crystal spectrometer were measured Int (hkl) of a series of Bragg reflectionsin diamond and LiF crystals of different perfection. Measurements were carried out inFe, Cu and Mo K - alpha radiations. Coincidence of calculated integrated intensities withInt (hkl) was attained by variations of empiric parameter D. The results show that in thegiven crystal one empiric para;meter D is sufficient to describe the experiment as to thewhole interval of the used wavelength and different Bragg reflections. Assuming that thesquare root from dislocation density is inversely proportional to D one can estimate thedislocation density in the studied crystals. The obtained values lie in the interval 5 x 105 -8 x 107 cnr2 for diamond and 6 x I06 - 8 x 108 cnr2 for LiF keeping with X-raydiffraction topographic data.

') . 4 . • ,

fi

POSTERS

IPROPERTIES OF CEMENTED CARBIDE WITH DIFFERENT Co CONTENT AND

DIFFERENT CRAINS SIZE OF TUNGSTEN CARBIDE FOR CONSTANT MEAN

FREEPATH

R. Porat, I. Gavish

Iscar, Israel

The aim of the project was to investigated the mechanical properties such as hardnessTRS nad fracture toughness of different compositions of cemented carbide from the groupof material related to die ISO K-35 application.

The composition has been prepared with a different cobalt content, different grain size inthe way that the composition of the finished sintered product will show mean free path ofthe cobalt in the range of 5 \xm.

The possibility to control the mean free path of the cobalt in the composition besides thedifferent cobalt content and the different grrain size is by preparing the material indifferent milling time to get different starting point of the tungsten carbide grain size.

The mean free path of the cobalt is related to the cobalt content and the specific area of thetungsten carbide grain size. In this case changing of the surface area and the cobaltcontent could help us to reach the constant value of the mean free path.

Normally the same mean free path will show the same hardness and the same fracturetoughness. We investigate all these different possibilities to see if can get optimumproperties.

Wli prepared the following procedure according to the required properties.

We mill different compositions composed on WC + TaC/NbC + Co. The reason is to addto the composition small amounts of TaC/NbC is to reach uniform structure and toeliminate grain growth. This was especially needed while we increased milling timewhich could cause the un-uniform structure and grain growth. For this experiment weprepared 4 basic compositions composed on WC + TaC/NbC + Co as follows:

CompositionsABCD

wt% WC88889090

wt% Co121088

wt% TaC-NbC2222

We av. grain size Jim (raw material)5559

The different materials A B C D have been prepared in different milling time to getdifferent wide range of X (mean free path of the cobalt). The thickness of X has beencalculated from the equation combining the coercive force, volume of the coblat and thegrain size of the tungsten carbide.

The material has been pressed and sintered and the mechanical properties have beenmeasured such as hardness, T.R.S. and fracture toughness.

Summarizing the result we found optimum mechanical properties in the followingcomposition:

10% CO + 2% TaC/NbC + 88% WC.

In this project we shall show the relation between mechanical properties, compositionstructure and grain size.

i i .

ASSESSMENT OF FATIGUE LIFE OF ALUMINIUM ALLOY COMPONENTS WITH

CRACKS USING RANDOM LOAD MONITORING SYSTEM

R. Arone, Sh. Ustilovsky, G. Sharshukov, A. Loksh, L, Potepun

Israel Institute of Metals, Technion R&D Foundation,

Technion City, Haifa 32000, Israel

A stochastic approach describing fatigue crack growth under random loads and

incorporating the closure concept for assessment of load interaction effects is presented.

Two extreme loading histories are considered:

(a) The superposition of overloads, random in time and magnitude, on base-line

constant-amplitude cyclic loading, and

(b) Random sequence of load peaks.

In the first case the model is based on presentation of the delay time due to retardation

effects associated with the overloads as a purely discontinuous Markov process. A

numerical procedure developed is based application of Kolmogorov-Feller

integrodifferential equation. An expression for failure probability is derived.

In the second case the load peaks are considered as a sequence of equally distributed

noncorrelated random variables. The crack opening stress, determined for an arbitrary

i th cycle, is estimated on the basis of the highest maximum and the lowest stresses

observed through n preceding cycles. It is shown that in this case some characteristic

integral of crack length is normally distributed. Numerical procedure developed accounts

for stochastic nature of both the load and the material. In order to verify the model a

computerized system for monitoring of simultaneous propagation of random arrays of

fatigue cracks has been developed. The panel-type sheet specimens with two rows of

single edge cracks (a row on each side) comprising up to 14 cracks (7 on each side) has

been used. Constant amplitude cyclic tests performed with the above arrays allowed to

evaluate stochastic parameters of material characteristics governing the crack propagation.

I1-1.4 ,

SOURCES OF ACOUTSTIC EMISSION IN AL-LI BASE ALLOYS Si

AND THEIR VARIATIONS WITH HEAT TREATMENT

F. Zeides, 1. Roman

The present report describes acoustic emission study of two Al-Li alloys. Al-Li alloys are

candidates for advanced structural applications, especially in aircraft and aerospace |industry. For this reason intensive development efforts are under way in several ',v

countries. The present work employed acoustic emission (AE) studies, as an important

support to traditional metallurgical analyses. Ae was registered and monitored during

either tensile or compression tests. It has been found that there are two major sources of i

AE in the studies alloys, namely, plastic deformation activity and constituent particles

failure. Both origins are sensitive to the heat treatment conditions, so that AE may be j££

used as a macroscopic tool for microstructural evaluation. . ;••

«

SELF- STRENGTHENING OF THE STAINLESS-STEEL UNDER SHOCK

LOADING

E. Zaretsky

Pearlston Center for Aeronautical Studies, Department of the Mechanical Engineering,

Ben-Gurion University of the Negev, POB 653, Beer-Sheva, 84105, Israel

The shock induced martensite formation in "marageing" and "marageing"-type alloys iswell-known phenomenon, e.g. 11], In the present work the behavior of stainless steel (of321-iype) near its dynamic fracture threshold at room temperature and shock inducedformation of martensite at temperatures from - 40°C up to - 100°C were studied. Thevelocity interferometer (e.g. [2]) was used for determination of dynamic mechanicalproperties (Hugoniot elastic limit - HEL, shock viscosity, spallation strength, elasto-plastic transformation hysteresis etc.) of shocked 10-irun width 100-mm dia stainless steelsamples. The shock (plane impact) was generated by the impact of 3-mm width steelimpactor accelerated by 57-mm-dia powder gun up to velocities 80-500 m/sec. The pre-shoted samples was cooled in situ by soldered copper pipe ring with liquid N2 throughdisposable rubber pipes. The cross-section of "soft-caught" after impact samples wasstudied metal lographically.

It was shown that the martensite which was formed due the shock induced deviatoricstresses is responsible for stainless steel HEL and spallation strength growth almost intwo times. The metallographica! studies of soft-caught samples showed a decrease ofmartensite transformation starting point from - 60°C in un-shocked samples up to - 20°Cin shocked ones.

The room-temperature impact experiments show an unknown anomalous growth ofstress-strain hysteresis at the impact velocities of about 80-100 m/sec which is close to thestainless steel fracture threshold of 130-140 m/sec. A model capable of explaining boththe phenomena is suggested. It based on dynamics of low-energy (10-50 mJ/m^)stainless steel stacking faults. It is shown that the process of voids nucleation due thereverse dislocation reactions with the Frank loops generation and their followingcoagulation is more realistic for the spallation fracture explanation than the mechanismbased on dislocation absorption by micro-cracks [3].

By the simultaneous analyses of both present work experimental data and open literaturefindings the significant role of partial dislocation motion accompanying the stacking faultsreproduction, growth and interaction is shown. In spite of comparatively low stackingfault energy the proper alloying of the material aimed at shock fault formation in everyplane of crystal lattice may lead to sufficient growth of its dynamics strength.

1. Chang S-N, Meyers M A Martensitic transformation induced by a tensile stresspulse in Fe-22.5 wt% Ni-4 wt% Mn alloy, Acta Metallurgica, 1988, 36, 1085-1098

2. Barker L M, Hollenbach R E Velocity interferometer for surface of any refractory,Journ. of Appl. Phys., 1972, 43, 4669-4675

3. Tong-Yi Zhang, Li J C M Interaction of a Screw Dislocation with an InterfaceCrack, Journ. of Appl. phys., 1991, 70, 744-751

PI .(.

DISLOCATION SOURCES IN SHOCK DEFORMATION OF METALS $

E. Zaretsky

Pearl ston Center for Aeronautical Studies, Department of the Mechanical Engineering,

Ben Ciurion University of the Negev, POB 653, Beer-Sheva, 84105, Israel

The mechanisms of high-strain-rate (with rates about 10 s - 109 s e c 1 ) plastic deformation jare not clear as yet; even in the simplest situations. For example, during the plane impact :;a high-speed transition from initial "one-dimensional stress" state to the final situation of •"hydrostatic compression" takes place. The high-speed relaxation of deviatoric stressoccurs immediately behind the shock front [1]. The known attempts to describe thisrelaxation in terms of solid-state dislocation theory were unsuccessful by the followingreasons: H

1. The existing dislocation concentrations in pre-strained material and the highest possible 4 idislocation velocities during the deformation (both being the factors of strain rate) are ^l;not enough for quantitative agreement with experimental data [2]. In addition, the ;;.shock-loading behavior of both initially dislocation-saturated and dislocation-free T jmaterials are very similar. •

2. Explanations including the processes of dislocation nucleation of multiplication aremore successful from the point of view of the strain rate description. However, they 'lead to two or three orders of magnitude surplus in dislocation concentration at the >final stage of the stress-relaxation process. To overcome this contradiction one needan additional artificial assumption of simultaneous nucleation of opposite-signdislocation [3] (annihilate during final stages of the shock loading).

The recent pulse X-ray diffraction measurements of structure variations of solids under ^shock loading | 4 | lead to better understanding of the stress relaxation mechanism. The '••-'lattice stacking faults (SF) bounded by the partial dislocation (PD) are responsible for thisrelaxation and almost all shear deformation in stacking faults.

The present work suggest a new theory of dislocation multiplication under effeci of shear jstress generated immediately behind the shock front. The theory based on the analyses ofPD motion under shear (deviatoric) stress effect, i.e. bow-out of pinned partial segment tohalf-loop, stretching of its lateral branches and these branches collapse with forming ofnew P D loop (bounding S F fragment) and a pinned half-loop ready to new act ofreproduction. The theory allows to estimate the rise time of a shock front, the residualpost-shock temperature and to predict elasto-plastic and fracture behavior of shockedmetal. v*

1. Swegle J W, Grady D E Shock Viscosity and the Prediction of Shock Wave Rise WTimes. Journ. of Appl. Phys., 1985, 59, 692-701 %.

2. Johnson J N Constitutive Relation for Rate-Dependent Plastic Flow in Polycrystalline mMetals. Journ. of Appl. Phys., 1969, 40, 2287-2293 §;

3. Meyers M A A Mechanism for Dislocation Generation in Shock-Wave Deformation. psScripta Metallurgies 1978, 12, 21-26 |3

P4. Zaretsky E B X-Ray Diffraction Evidences of Stacking Faults Role in Plastic j$

Deformation of Solids under Shock-Wave Loading Shock Waves, 1993 (accepted forpublication).

I'l . 7

LOCAL REINFORCEMENT OF METAL CASTINGS WITH CERAMIC

FIBRES /PARTICLES

B. Barkai, N. Kami

Israel Institute of Metals, Technion Research and Development Foundation, Ltd., HaifaIsrael

Metallic composite materials (MMC) are increasingly occupying an important position inmodern industry. Including of ceramic fibres or particles in the metallic matrix produces amaterial with improved properties, such as hardness and resistance to abrasion, ascompared with the matrix material. Local reinforcement of castings permits utilization ofthe advantages of MMCs confines to the regions where the particular product requiresthem while leaving intact the desirable properties of the base metal, e.g. machianabilityand ductility, over the rest of the product.

This paper summarizes a number of research projects carried out by the authors in thecourses of the past few years and dealing with the development of preparation methodsand the investigation of the properties of aluminium and zinc alloy castings reinforcedwith alumina fibres or silicon carbide particles. The reinforcement fibres are introducedinto the metal as a mass of compressed fibres (preform), which contains about 20% fibresand 80% air spaces. The reinforced portion forms an integral part of the casting. Frommetallographic observations made in the boundary zone, metal/MMC, it became clear thatthe microstructure of the metal remained unaffected by the contact with the reinforcementfibres, while no clear dividing line was formed separating the metal from the MMC in theboundary region. There is good penetration of the metal into the air spaces between thefibres; all the spaces are filled with mertal, so that close contact has been establishedbetween the metal matrix and the fibres.

Silicon carbide particles were introduced by a similar method. In research carries out bythe authors the investigation focused on the possibility of placing the mass of fibres indifferent areas of the casting. The results showed that the penetration of the metal into theinterstices between the fibres was good and independent of the location of the fibrepreform in the casting.

Hardness tests of the specimens of alumina fibre reinforced aluminium matrices showedthat the MMC regions of the specimens tested as cast are very hard as compared with theareas of the rest of the metal.

Tensile tests were made with specimens taken from the cast part in such a manner thatthey contained, at their centre an MMC aera and, at their ends (where they held by thetensile machine) - metal only. The results of these tests point to a lower fracture stressand a reduced ductility a compared with specimens consisting only of metal.

An examination of the fracture face under a scanning electron microscope (SEM) showedthat in all the specimens the fracture occured in the boundary region between the metal andthe reinforcement layer.

In specimens of a zinc alloy matrix with silicon carbide reinforcement the changes inproperties exhibited similar tendencies. Comparative wear tests showed that reinforcedmatrix specimens withstood abrasion better than unreinforced matrix specimens.

] ' \ .

FORMATION OF Co AND Ta SILICIDES ON Si (100) AND Si (111)

SUBSTRATES FROM CODEPOSITED Co AND Ta FILMS

S. Darwish and J. Pelleg

Ben Gurion University, Department of Materials Engineering, Beer Sheva, Israel

The silicides are used in the microelectronic industry as interconnecting lines and as

contact material. The silicides have low resistivity and they are characterised by good

thermal stability. In ternary systems of refractory metal - near noble metal - and silicon

(in some experiments the substrate is the third component, i.e., silicon) after annealing at

temperatures above 700°C disilicides are usually on the top of this layer. The near noble

silicide near the silicon substrate is used as shallow contact, and the refractory silicide on

the top of this layer p protects this contact. The low resistivity of the near noble silicide,

and the high thennal stability of the refractory silicide make such a system valuable in the

semiconductor industry. In this work we investigated the formation of cobalt and

tantalum disilicides from co-deposited film of Co and Ta by electron gun deposition on

silicon substrates N-type <100> and <111> to a thickness of 1500 A. The formation

investigated at temperatures range 700-1000°C by hot X-ray diffraction (in situ) and rapid

thermal annealing (RTA). The phases indetification was done by the above techniques.

The difference in the rates of formation of the silicides was observed between phases on

Si <100> and <111> substrates. No reports on the Co-Ta-Si system were yet published.

PROBABILISTIC PROCESSES AND FORMING STRUCTURE DURING

SOLIDIFICATION

D. Kopeliovich

It is known, that distribution of defects in a metal product has a probabilistic character,

that results in statistical description of its quality (durability, reliability). However

solidification, which considerably determines formation of these defects, is usually being

described by deterministic ways. It makes difficult to prognosticate distribution of

defects.

In this work a probabilistic concept of solidification has been developed. It is proved that

solidification parameters (cooling rate, temperature gradient, solidification rate etc.) are

random magnitudes. Role of fluctuations in selforganization during solidification is

considered. The probabilistic concept has been used for developing imitative models of

solidification. Two kinds of model are developed. The discrete model simulates a wide

range of structures: from monocrystal to amorphous. The continual model considers

transferprocesses which take place in the transient zone of crystallization. A further

imitative model is for the simulation of forming dendrite. This model is based on the

assumption of a random character of supercooling. It yields branchy structures that

become more even as local negative supercooling gradient decreases. The probabilistic

concept has been used for creating the method of prognostication of A - segregation in

steel ingots. The method allowed to prevent appearance of this segregation in critical

points of the nuclear power plants. Influencing of cooling rate and chemical composition

upon dendritic structure parameters was investigated by experiment. An experimental set

up for influencing upon solidification by means alternating electromagnetic field has been

designed.

it1M . I f )

INFLUENCE OF GRAIN BOUNDARY SEGREGATION ON THE

THERMOPH YSIC AL PROPERTIES OF CERAMICS x

Tatiana Gambaryan, Efim Ya. Litovsky and Michael Shapiro

Faculty of Mechanical Engineering, Technion - Israel Institute of Technology

Haifa 3200, Israel i

Heat transfer in porous ceramics is accompanied by diffusion of various kinds of

impurities, normally present in all crystalline materials. These impurities tend to

concentrate (segregate) from the bulk onto surfaces of small pores, existing in the region

separating two sintered crystalline granules. Under the influence of an externally applied

temperature gradient the impurities diffuse in the bulk and along the pores' surfaces.

These diffusion-segregation processes are accompanied by heat release and absorption,

occurring on the opposite sides of the pores. These processes are shown to affect the

temperature field near the pore and, hence, the effective thermal conductivity of ceramic

materials.

A simple model of heat transfer in porous ceramics in the presence of segregation-surface

diffusion mechanism is proposed. The effective thermal conductivities of materials

possessing a small amount of spherical or cylindrical pores are calculated, which are

shown to generalize the well known Maxwell formula for conductivities of composite

materials. Nondimensional parameters are formulated which govern the relative influence

of segregation and diffusion of impurities on the effective conductivity of porous

materials.

Estimates performed for several Arrhenius type surface isotherm formulas, relating

surface and bulk concentrations of impurities, show that the segregation-diffusion

mechanism satisfactorily describes abnormal temperature dependences of thermal

conductivities of refractory oxides in vacuum. However, for atmospheric pressure the

effect of this mechanism is dominated by gas conductivity in pores.

Analyses of influence of grain boundary segregation-diffusion processes on the

thermophysical properties of ceramics possessing various compositions and

microstructures were performed. It was shown that this mechanism is most significant

for temperatures exceeding 1500°C and for measurements in vacuum in the temperature

range from 400 to KKXTC. ;

' i . i:'

TEMPERATURE AND GAS PRESSURE DEPENDENCES OF THERMAL

CONDUCTIVITY OF DENSE AND INSULATING CERAMIC MATERIALS

E. Ya. Litovsky, M. Shapiro

Faculty of Mechanical Engineering

Technion-Israel Institute of Technology, Haifa 32000

Porous ceramics and refractories are widely used in metallurgy, insulating constructingmaterials, space technology, high-temperature furnaces, etc. Operating conditions ofsuch materials cover wide ranges of temperatures (T), pressures (P) and gascompositions. Investigation of thermal properties of ceramics are essential in designingand optimization of various high-temperature aggregates and materials, possessingpredetermined thermal properties.

Analysis of experimental data are presented, which where obtained for thermalconductivities X(P, T) and thermal diffusivities a(P, T) of high temperature oxide ceramicmaterials with porosity 5-98%, obtained for temperatures 5OO-25OOK and gas pressure1()-2 - 2 • 107 Pa. These results reveal several abnormal effects in behavior of X(P, T)and a(P, T), which can not be explained on the basis of known classical mechanisms ofheat transfer in porous materials, the latter include heat conduction in solid and gasphases, radiation and gas convection within the pores. It was found that X.(T) exhibitscomplicated nonmonotonic behavior. This contradicts the results of classical experimentalinvestigation of X(T) for dense crystal ceramic materials which decrease with increasingtemperature (Eiken's law). The latter dependence was not observed for porous materialsin rarefied gases. The dependence of X.(P) and a(P) upon the gas pressure at hightemperatures is qualitatively different from that observed for low temperatures. Inparticular, it was found that a(P) increase with decreasing gas pressure. For insulatingrefractories thermal conductivities was found to be complicated function of porosity,pores and particle sizes.

The above effects are qualitatively explained by a combination of the classical and newheat transfer mechanisms, related to heterogeneous heat and mass transfer processoccurring at the grain boundaries of dense ceramics, and heat radiation scattering forinsulating refractories. The novel heat transfer mechanisms include segregation-surfacediffusion of impurities along grain boundaries and pore surface and gas transport, arisingfrom chemical conversion in pores.

Analysis and classification of the pressure-and temperature dependences of thermalconductivity for various refractories and ceramic materials on the basis of the fractalmodel of porous materials structures and the above mentioned heat transfer mechanisms.Pressure- and temperature dependences of thermophysical properties of dense refractories

i . i i

I SYNTHESIS OF IRON, NICKEL AND COBALT TITAJVIDES FROM FINE

t ELEMENTAL POWDERS

I''' E. Paransky, I. Gotman and E.Y. Gutmanas

I- Department of Materials Engineering, Technion, Haifa, Israel

Iron, nickel and cobalt titanides were synthesized from consolidated to full density micron

size elemental powder blends (Fe, Ni, Co-Ti). Consolidation was performed by cold

sintering (high pressure consolidation at ambient temperature) at pressures considerably

lower than those required for consolidation to full density of the prealloyed intermetallic

powders. Subsequent homogenization heat treatments resulted in solid state reactive

synthesis of the corresponding titanides. Synthesis of a titanide of the final stoichiometry

was accomplished through the formation of intermediate Fe, Ni, Co-Ti phases of different

stoichiometry, and its kinetics were controlled by the diffusion of components through

these phases. Reactive diffusion processes in Fe, Ni, Co-Ti powder systems were

studied on model structures - a Ti foil partly or fully embedded in a Fe, Ni or Co powder

and, vice versa, a Fe, Ni or Co foil/thin sample embedded into a Ti powder. Based on

the model experiments, the synthesis heat treatment parameters were chosen. The effect

of processing parameters on the microstructure and mechanical properties (hardness, yield

strength at elevated temperatures) of obtained titanides was investigated. X-ray

diffraction, SEM/EDS and TEM/EDS employed for microstructural investigations showed

that the titanides obtained had very fine homogeneous microstructure with

micron/submicron grain size. Solid-state reactive synthesis from elemental powder

blends may be used for production of close to net shape full density titanide intermetallic

parts.

l'l . 14

DEVELOPMENT AND CHARACTEREA1TONS OF COMPOSITE SOLID

ELECTROLYTE FOR BIPOLAR LITHIUM BATTERIES FOR ELECTRIC VEHICLES

E. Peled and D. Golodnitsky

Our goals are to develop and characterize a small laboratory prototype of a new bipolar

lithium battery for electric vehicles and energy storage. This rechargeable battery consists

of thin foils (about 10-5011 thick) of lithium anode, composite solid electrolyte (CSE) or

composite polymer electrolyte (CPE), composite cathode and bipolar Ni based current

collector.

This paper describes materials fabrication and evaluation for the CSE, CPE and the

composite cathode. Our CSEs and CPEs mechanically stable, have very good

compatibility towards lithium, good ionic conductivity (10"5 - 10"3 ohm"1 cm 1 at 110°C),

low and stable interface lithium/CSE resistance (10-50 ohm cm2 at 120°C for up to 1000

hi). The conductivity of our CSEs and CPEs at high salt concentration is one to two

orders of magnitude higher than the state of art polymer electrolytes. For some

compositions the lithium transfer number is closed to 1. Several Li/CSE batteries were

cycled (charge-discharge) for over 60 times.

CAPACITORS WITH GRAIN BOUNDARY BARRIER LAYER MICROSTRUCTURE

IN THE BaO - (SrO) - TiO2 AND BaO - SnO2 -TiO2 S YSTEMS

V. Stancovski, M. Kravchik, A. Goldstein, A. Bar

Israel Ceramics and Silicates Institute, Technion City, Haifa

The fast miniaturization of electronic circuits requires the development of capacitors with

high volumetric efficiency. In the case of the lower operating voltages, grain boundary

barrier layer capacitors, utilizing very thin dielectric layers, are of great interest. Grain

boundary layer (GBBL) microstructures are characterized by semiconductive grains

enveloped by insulating layers. At the macroscopic level, this results in an effective

dielectric constant 1-3 orders of magnitude higher than the intrinsic dielectric constant of

the material in question.

The traditional synthesis of GBBL devices, involves a iwo stage sintering process: the

first stage is a reduction, followed by controlled cooling down to room temperature.

Semiconductive pellets are obtained at this stage of the process. A chemical treatment has

to be done in order to provide the dopant ions involved in the formation of the barrier

layers at the level of grain boundaries. The formation of the GBBL microstructure is

achieved by a second thermal treatment, under oxidizing conditions.

A single stage process, which does not involve a complicated chemical treatment of the

reduced pellets and is compatible with the multilayer technique, is presently being

investigated. The processing conditions, regarding parameters such as: composition of

ceramic powders, atmosphere conditions and thermal treatment schedules, are examined.

I ' l . I f ;

iEFFECT OF HEAT TREATMENT CONDITIONS IN ALUMINIUM - MATRIX

COMPOSITES

C. Alexandru*, P. Moldovan* and G.V. Ghica**

*Department of Science and Eng., Polytechnic Institute,Splaiul Independentei, nr. 313, Sector 6, Cod. 77206,

Bucharest, Romania**INTEC - SA Bucharest, Romania

The purpose of the present study is to examine the role of the heat treatment conditions on

the microstructure and microhardness of the paniculate reinforced Aluminium-matrix

composites.

The composites containing up to 20 vol. % A12O3 and SiC particles, was processes via a

molten metal mixing route and then cast, heat treated in various conditions.

The microstructural development during heat treatment was studied using optical and

Scanning Electron Microscopy (SEM).

The microhardness results were plotted against aging time, at a different temperatures, to

obtain the aging curve.

PI . I 7

INSITU QUALITY MONITORING TECHNIQUE FOR A HIP PROCESSO. Tevet*, O. Yeheskel**, V. Atzraony**, and M.P. Dariel**

"Nuclear Research Center, P.O. Box 9001, Beer-Sheva, Israel 84190*Ben Gurion University of the Negev, Beer Sheva, Israel

Hot lsosiatic Pressing (HfP) is one of the most important processes in powder

metallurgy. In this process powder of the material, enclosed in a canister, is

simultaneously subjected to high pressure and high temperatures during a certain

period of time. Due to this treatment the material is densificd. The details of the

process regime strongly depend on the specific material and are usually obtained

alter a costly and long procedure. A possibility to monitor the quality of the

material during the densification process wili help to save time and money.

Herewith a technique for insitu monitoring this quality is described. It is based on

a sound wave velocity measurements of the material during the process. Comparing Ibe

sound velocities in the material to the velocities expected in a fully densified

sample under the same conditions (reference velocity) gives an indi :alion lo the

material quality. In order to derive the velocity in the material one has lo divide

the longitudinal dimension of the material by the "time of flight" of Ihe sound

through it, which is the value measured by the technique. This dimension changes

during the densification process due to both the change in the material density and

the canister deformation.

In the present work methods lo predict the dimension changes during the HIP process

arc shown. Also arc discussed the theoretical based methods to derive the reference

sound velocities under the process parameters from known values under other

conditions. This technique enables a modification of the Ashby's densiticalion

prediction model as will be shown. Results of applications of this technique during

real HIP processes will be given.

IM . I li

MICROSTRUCTURAL EVALUATION OF CAST ALUMINIUM ALLOY MATRIX

COMPOSITES

P. Moldovan*. C. Alexandra* and G.V. Ghica**

*Department of Science and Eng., Polytechnic Institute,Splaiul Independentei, nr. 313, Sector 6, Cod. 77206,

Bucharest, Romania**1NTEC - SA Bucharest, Romania

Aluminium alloy matrix composites with A1203, SiC and Graphite participates were

synthesized using liquid metallurgy route.

The microstructure of the composites were analysed using optical, Scanning Electron

Microscopy (SEM) and energy dispersive microprobe (EDX).

Several phenomena which influence solidification in unreinforced casting are modified in

the presence of high volume fractions of the reinforcing phase.

The evaluation of matrix structures was influenced by particle segregation due to settling,

particle-solidification front interactions and interfacial chemical reactions was discussed.

The nucleation of primary silicon on ceramic particles in AlSi matrix composites is widely

observed. In the presence of magnesium there is a relatively high probability that the

graphite particle surface will be suitably oriented, with respect to silicon, to form a iow

energy interface with it and act as substrates for heterogeneous nucleation.

PI . 19

UNUSUAL MECHANICAL PROPERTIES OF HIGH-STRENGTH ROLLED STEEL

WITH MACROANKOTROPIC STRUCTURE

P.D. Odessky, S.I. Morozov, M.R. Uritsky, A.B. Steblov and V.T. Chernenko

Currently available on a commercial scale is hot-rolled steel strengthened in a special

chamber-type installation directly ahead of the runoff table, the heat treatment consisting

of surface cooling at rates as high as ~ 1000°C/s using turbulent water jets. Then the

metal is tempered on the runoff table at the expense of heat accumulated in the axial zones.

This rolled stock is made of conventional low-carbon or low-alloy structural steels used in

mass production.

The surface layers (up to 1 mm) acquire the structure of tempered martensite, whereas the

core has the structures formed on diffusion type y -» a transformation. The result is

structural macroanisotropy over the cross-section of steel. Normally, the hardness of

surface layers exceeds that of the core by = 100 HV. The residual compression stress in

the surface layers is as high as <= 100 N/mm2. The yield strength of steel is in the range

from 350 to 630 N/mm2 depending on steel composition and cooling conditions.

The property levels given above are average values and actually vary, for instance, in

angle steel with 8 mm flange as follows: ay = 560 N/mm2 , a u = 660 N/mm2 for the

overall cross-section ; ay = 600 N/mm2, au = 685 N/mm2 for 3 mm thick test pieces cut

from surface ; Oy = 455 N/mm2 , ou = 520 N/mm2 for the core zone.

The peculiar protective effect of the more compressed higher strength surface zones by

structural macroanisotropy is often responsible fo the unusually high mechanical and

performance properties of rolled stock.

MAGNETOCHEMISTRY OF THE TETRAHALOFERRATE (III) IONS IN THE

A3Fe2X9 SERIES

Roey Shaviv*, Richard L. Carlin**

*TAMI (IMI) Institute for R&DP.O. Box J0140 Haifa Bay 26111 Israel

**Department of ChemistryThe University of Illinois at Chicago

Chicago IL 60680 USA

The magnetic properties of the tetrahaloferrate (HI) ions at elevated temperatures are

paramagnetic and straightforward as expected from the 6A1 ground state with S = 5/2 in a

(quasi) octahedral symmetry. At lower temperatures (below 10 K), where

superexchange interactions become dominant, these materials tend to order as

antiferromagnets. Specifically, for compounds of the stoichiometry A3Fe2X9 where A

takes the form of

|4-Y(py)H|+ (X = C1-, Br-; Y = H, CJ, Br; py = pyridine) the symmetry the ferrate ion is

subjected to deviates from that of a perfect octahedron and the small unisotropy which

results gives rise to spin canting in the magnetically ordered phase. The extent of short

range magnetic ordering in these series appears to be dependant on Y whereas the critical

temperature appears to be more strongly dependent on X-. Single crystals of several

compositions in this series were studied by XRD, ac magnetic susceptibility, and

calorimetric experiments. The results of these experiments will be presented and the

magnetochemistry of the series will be discussed.

Acknowledgement: This work was performed at the University of Illinois at Chicago and

was funded by the National Science Foundation (USA) under DMR-8815798.

STRUCTURE AND PROPERTIES OF RAPIDLY SOLIDIFIED GOLD - TITANIUM

ALLOYS

T. Aboud and D. Shechtinan

Technion, Israel Institute of Technology

Department of Materials Engineering, Haifa 32000, Israel

This study concerns the development of rapidly solidified dilute gold alloys with a view to

producing enhanced mechanical properties that should prove beneficial to the jewellery

industry. Four alloys were melt spun: 1 wt.% Ti, 2wt.% Ti, 3wt.% ti and 5wt.% Ti.

On etching polished cross-section in Aqua-regia all of the melt spun alloys were found to

show transitions in structure associated with a change in: (a) solidification rate, (b)

response to etching, (c) preferred orientation, (d) phase transformation and (e) grain size.

It was found that (Ti) content causes a change in the ribbon formation mechanism; their

sponsor is shown to be critically dependent on the thermal conductivity of the specific

alloy.

Two classes of TEM studies had been individually on flat-on and cross-section samples.

The first is on regions of alloy which were electron transparent directly after melt spinning

without further thinning being required, whilst the second is on alloys which were

thinned subsequent to rapid solidification and hence are more representative of the bulk of

the alloys. In accordance with, the microstructures observed by SEM and the phases

detennined by X-ray diffraction (for both sides); full matching had been reported by the

later class.

The microstructures of the rapidly solidified dilute Au-Ti alloys and their response to post

solidification heat treatment is discussed with reference to their mechanical properties.

The properties of the as-solidified and heat treated alloys are shown to be determined by

the solute content critically dependent on the degree of super saturation achieved and the

size/morphology/density of precipitates presents.

As predicted by rapid solidification theory, it was observed that the pre-mell spun alloys

showed a highly segregated microstructure; whilst for the melt spun alloys a high degree

of super saturation have been achieved.

Enhanced mechanical properties have been achieved and the active hardening mechanisms

are found to be solution hardening and precipitate hardening.

I MICROSTRUCTURAL AND COMPOSITIONAL CHARACTERIZATION OFi TiW/AI-0.8%Si/TiW/PtSi/(100)Sia

j A. Ashkenazi*. Y. Komem* and I. Lerner**

I *Department of Materials Engineering, Technion, 32000, Israel

•National Semiconductor, Migdai Haemek, 10566, Israel

The microstructure and composition of a contact, composed of an outer layer made of

(30nm) TJ3W7, an intermediate layer of (550nm) AI-0.8%Si, a diffusion barrier layer of

(90nm) T13W7, and a platinum silicide layer (about 50 nin thick) as an interconnect to the

(100) Si substrate, were studied after heat treatments at temperatures between 400 and

5(KrC. The contact microstructure was characterized by X-ray diffraction, Auger Electron

Spectroscopy, Electron Microscopy and Secondary Ions Mass Spectroscopy. Special

attention was given to the study of the correlation between the stability of the layered

structure and the electrical properties of the contact, such as sheet resistance and contact

resistance. It was discovered that the contact microstructure was not stable during the heat

treatments, and diffusion processes of Al, Ti, W and Si are taking place. The first species

to diffuse are Ti and W, from the inner and the outer TiW layers, at 400°C. This process

is followed by some solid state reactions that create aluminide phases like AI3TJ, Al^W

and AJ5W. At 475°C, the inner TiW diffusion barrier layers fails and Al starts to diffuse

through it into the silicide layer. Consequently Al decomposes the PtSi layer and reacts

' with Pt to form the Al2Pt phase. The formation of this phase is followed by volume

increasing which causes an upward bending of the inner TiW layer and fonnation of

cracks. Total decomposition of the PtSi layer is found at 525°C and enables diffusion of

Si from this layer into the Al layer.

The microstructural changes during the heat treatments, like decrease in the Al layer

thickness and formation of new phases with high resistivity like AI5W causes an increase

in the sheet resistance. The replacing of the PtSi/Si contact by the Al2Pt/Si contact which

has a lower Scholtky barrier height cause a decrease in the contact resistance. At 55O°C the

contact fails as a result of A] .spike formation in the Si substrate.

Ik

£ UTILIZING ACOUSTIC - EMISSION AS A NON - DESTRUCTIVE METHOD FOR

I PRESSURE VESSELS

f A. Mittelman

\ School of Applied Science' Hebrew University

Jerusalem

There are several Non Destructive Testing (NDT) methods that are employed in

engineering applications and industry for quality control examination. It is well known

that each method has its advantages and disadvantages. The mode of decision regarding

NDT inspection in critical engineering components is generally based on correlation of

NDT data from at least two independent methods.

In this article the implementation of Acoustic Emission (AE) as a NDT method tat found to

be much more reliable, simple to analyze and easy in utilizing than Ultrasonic (US) and X-

ray for an industrial problem will be shown.

The paper will apply to a problem in the field of pressure vessels.

Pressure vessels were generally examined non destructively by using US and X-ray. In

some vessels the indications of the US were indeterminate and in the X-ray were negative.

The quality control authorization required that the results of the two methods will have

negative results. The US results indicated that there might be a problem but the X-ray

indicated that the vessels are okay.

Analyzing the AE activity of those vessels during proof tests gave clear results in sorting

the vessels. Monitoring and analyzing the RMS (root mean square) of the AE enabled us

to distinguish between sound and defected vessels. The separation was conducted by

' monitoring the AE activity from the onset of loading. It was found that the degree of

severity of the defects in vessels affect the AE activity already in low load levels.

P] . 2 4

i Au-Cu-Cd ELECTROPLATED ALLOYS STRUCTURE AND MECHANICALf, PROPERTIESI> S. Libov, Eva Igner

f Jotaly Ltd.

Electroplated gold alloys have a great importance in electronicjewellery and other

industries. The binary system Au-Cu is well known in the literature and a large number of

papers deal with it, whereas the ternary system Au-Cu-Cd is much less known. Cd has a

great influence on the mechanical (physical) properties, colour and structure of this alloy.

Au-Cu-Cd system is the subject of this presentation and the results obtained are discussed.

The mechanical properties such as hardness, plasticity and physical properties such as

_ density were measured and studied. The structure of these deposits were investigated

using X-ray diffractometry. Au-Cu-Cd deposits give the X-ray spectrum of FCC lattice

where Au and Cu are oriented according to the Bravais type lattice and Cd is presented as a

defect in the vacancies or in the grain boundaries. X-ray analysis of the Au-Cu-Cd

deposits show an asymmetrical broadening of the main line peaks which eventually is

eliminated after the annealing heat treatment. Since the background is constant in both

spectra (before and after the heat treatment it can be assumed that Cd and the vacancies

move into the grain boundaries in the low temperature state. This assumption is supported

by the fact that the deposit density does not change as well as its microscopic structure as

illustrated in the SEM pictures and EDS analysis.

The mechanical properties are changed significantly by the heat treatment e.g., the deposit

becomes less brittle - plastic and hardness is also decreased.

•* This investigation shows that by choosing the adequate deposit composition and by

performing the optimal thermal treatment the desired mechanical properties can be

obtained.

PROCESSING OF A HIGH - PURITY ALUMINA MATERIAL

O. Glozman, L. Baum, W.D. Kaplan, and D.G. Brandon

Dept .of Materials Engineering, Technion-Israel Institute of Technology, Haifa, Israel

Alumina is possibly the most intensely studied ceramic system. Despite the vast amount of

published work, every alumina powder has to be studied and adapted to specific and

available equipment.

The primary objective in the sintering of high-purity polycrystalline alumina is to maximize

the material density, while preventing abnormal grain growth, The purpose of the current

study is to optimize the processing of high purity alumina powders into a high density

product. Several powders of commercial alumina were tested: the specimens were

prepared by filter-pressing of aqueous slips.

Low viscosity and high solids content slurries were prepared and optimized by latin

squares analysis. A dense green compact was formed, by controlled rate filter pressing.

The final sintered density was, as expected upon the initial green density of the specimen.

Pre-coarsening treatments and the effect of sintering rate were also examined. Preliminary

experimental results will be reported.

PI.26

THERMOMECHAN1CALLY STRENGTHENED SHAPES FOR BUILDING

STRUCTURES MADE OF LOW-CARBON AND LOW-ALLOYED STEEL

A. Klyuch

Department of Materials Engineering, Technion,

Israel Inst. of Technology, Haifa 32000

Thermal strengthening of steel shapes made from low-alloyed and low-carbon steel

during their hot rolling seems to be of the most effective technologies. The production of

such a metal is implemented in industrial conditions for the following kinds of shapes:

angles, I-beams and channels.

The main stage of the process is interrupted quenching with the following self-tempering.

A heterogeneous microstructure is formed in the cross-section of the shape. The metal

has a structural anisotropy and could be assumed as a composite material.

One of the most important tasks of the research was to find a possibility of application of

such a material in welded metal structures. For this reason the studying of these steel

shapes has been performed both for the as-received condition and after welding.

The rolled metal possesses a high homogeneity of its mechanical properties. For example

for the 100 x 100 x 10 mm angles made of low-carbon steel yield stress ay = 460

MPa and the standard deviation S o y = 16 MPa. The resistance of the investigated

material to brittle fracture is extremely high, e.g. U-notch Charpy impact toughness at

temperature minus 70°C for the 75 x 75 x 8 mm angle made of low-carbon steel is

1.36MJ/cm2.

The simultaneous increase in strength and fracture resistance should be explained by the

presence of specific multilayer microstructure.

PI . 2 7

PERFORMANCES AND WEAR PHENOMENA OF THE TiN-COATED TWIST

DRILLS

Dan Mean, Ladislau Kerekes, Mariana Carean

Technical University of Cluj-Napoca, Bd-ul Muncii 103-105, 3400, Cluj-Napoka,Romania

One of the most serious problems in today's industry is the improvement of productivity.

This is reflected by an important increase in the use of numerically machine tools and

flexible manufacturing systems.

Consideration has to be given to developing tools with longer life. The TiN-coated tool

has great potential for improving the performance of manufacturing systems.

The paper presents a comparative experimental study of the performances of conventional

HSS drills and TiN-coated drills during the drilling of austenitic stainless steel.

The results obtained revealed a great difference in performance between uncoated and

TiN-coated drills; TiN-coated drills showed much superiority.

The comparison of the axial forces and torque showed that using TiN layers, the decrease

of the forces is about 5-8%, and of the torque about 15-20%.

The average tool life of the TiN-coated drills was almost six times longer than the tool life

of the conventional HSS drills.

The microscopy of the tool surface showed that TiN-coated drills didn't present craters

and built-up edges, but some cracks were observed running parallel to the cutting edge.

Titanium coatings, due to their low friction and small thermal conductivity, act improve

tool performance by reducing adhesion and lowering the wear of the tool surface.

PI . 2 8

ji SOLID STATE AMORTIZATION OF Cu-Ti-B POWDER SYSTEM BY

I MECHANICAL ALLOYING

f M. Savransky, S. Berger and B.Z. Weiss

| Dept. of Materials Engineering, Technion, Israel Institute of Technology, Haifa, Israel

A mixture of elemental powders of copper, titanium and troron was mechanically alloyed

for the purpose to study the mechanism of solid state amorphization. Three different

compositions and various milling times for each composition were applied. The

microstructural, compositional and surface morphology changes occured during the MA

were investigated by Scanning Electron Microscopy, Transmission Electron Microscopy

combined with Energy Dispersive X-ray Spectroscopy, X-ray Diffraction and Differentia!

Thermal Analysis.

It was found that two amorphous alloys were formed as the result of MA. Both alloys are

composed of only two elements Cu-Ti. However, the first alloy contained mainly copper

while the second contained mainly titanium. The amorphous phases were dispersed

homogeneously in the powder system surrounded by nano-crystalline grains of copper

and titanium. The microstructure of the boron grains was not affected by the mechanical

alloying and no interaction between boron and/or copper and/or titanium was observed.

The quantity of the amorphous phases increased with increasing milling time until a

steady state was reached. The increase of copper in the system from 60wt% to 80wt%

lead to a decrease in the quantity of amorphous phase. In the system containing 95wt.%

Cu no amorphous phase was observed. The enthalpy change associated with the

crystallization of the amorphous phases was measured and correlated with the

microstructural changes.

STUDY OF CHEMICAL VAPOR INFILTRATION PROCESS FOR SiC MATRIX

COMPOSITESi: N. Nawi, D. Itzhak, U. Admon and M.S. Dariel

I Nuclear Research Center-Negev and Ben Gurion University

^ Ceramic Matrix Composite materials are well known for their high strength-to-weight

ratio and fracture toughness. Conventional techniques for the fabrication of ceramic

composites, such as sintering and hot pressing, involve mechanical stress and chemical

damage to the fibers. One of only a few processes to fabricate ceramic composites

without chemically or mechanically damaging the fibres is C.V.I (Chemical Vapor

Infiltration), which is directly derived from C.V.D (Chemical Vapor Deposition). CVI

and CVD allow the formation of complex geometries and produce very high melting point

materials at medium and even low temperatures. Current isothermal commercial CVI

processes suffer from major problems such as surface sealing, slow densification and

density gradient in the product. Temperature gradient, forced-flow CVI1"3 reduces the

infiltration time and the density gradient significantly.

In this process efficiency of infiltration and yield are limited by (a) residence time

(inversely proportional to gas velocity), (b) reaction rate (proportional to temperature in

the MTS system), (c) unhotnogeneous gas flow distribution and susceptor configuration,

(d) blocking of infiltration through formation of impervious internal layers in early stages

of infiltration and by extraneous growth of deposits on the surface of the preform.

The following is a preliminary report of CVI experiments, performed on graphite fiber

preforms under the following conditions: graphite fibrous preforms were retained within a

graphite holder in contact with a water-cooled metal gas distributor, thus cooling the

bottom and side surfaces of the substrate. The top of the fibrous preform was exposed to

the hot zone of a graphite susceptor which resulted in a thermal-gradient of up to

2500°C/cm in the preform. The reactant gases, MTS (methyltrichlorosilane - Ar as a

carrier gas), H2 and Ar passed through the cold portion and towards the hot portion of the

preform, where they decomposed, to form SiC matrix:

CH3SiCl3 (MTS) = SiC + 3HC1 (Excess H2, Ar)

HIGH TEMPERATURE PERICLASE INSULATION

I. Yaniv, R. Cytermann, T. Litovsky

IMI (TAMI) Institute for Research & Development Ltd

' One of the basic requirements expected from technical processes-especially high-

temperature processes-is the rational application of energy. Therefore, development of

high refractory insulating materials for applications at up to 2000K is of importance for

engineering and technology.

This work is concerned with the development of high temperature insulation technology

on the basis of high purity periclase by the foam method. The high melting point of MgO

and the availability of raw materials in Israel nidke this technology economically feasible.

The main objects in technology development were creating an optimal material structure

corresponding to minimal thermal conductivity and insuring high strength at low reheat

change at elevated temperatures.

Two basic practical requirements for high-temperature heat insulating materials were used:

the porosity should be as large as it possible and the pores should be as small as possible.

In order to achieve the desired properties the following technological investigations were

carried out: optimization of conditions for initial material preparation, mixing conditions,

foam formation and drying and sintering conditions.

The technology developed allows to obtain a porous material structure with a porosity in

the range 60-80% and particle size 1-10 \xm. Material strength is related to the porosity

which in turn, may be adjusted by the process. The particle size distribution provides for

large scattering of heat radiation and, as a result inhibits increase in effective thermal

conductivity at high temperatures.

As a result of performed investigation the technological parameter permitting to obtain

high-temperature heat insulation on the basis of MgO with predetermined properties were

found.

P J . 3 1

INTERNAL RESIDUAL STRESSES AND WEAR RESISTANCE PROPERTIES OF

COMPOSITE NiCr ELECTROCHEMICAL DEPOSITS

S. Eskin, O. Berkh, J. Jahavi, J. Lanfir, L. Zevin

Wear resistance, microhardness and residual strains and stresses of Cr-Al2O3 and CrNi-

AI2O3 electrodeposited composite coatings were investigated as a function of AI2O3

concentration in electrolyte and deposition current density. Composite coating were

produced from electrolyte on N, N-dimethylformamide base. For codeposition

corrundum particles (a- AI2O3) were used with average particle size of 5 |J.m. Wear rate

was estimate as a result of mass loss with sliding distance. Worn surfaces were examined

by means of microscopic observation.

As shown minimum wear rate was achieved at AI2O3 amount in electrolyte of 15-110 g/1.

In the absence of particles the wear rate was 4 time of minimum wear rate. The increase

of AI2O3 amount up to 150 g/1 resulted in 3.0-3.5 fold reduction of wear resistance.

Microhardness of composite Cr and CrNi coatings did not exceed 650-750 HV and

actually did not depend on AI2O3 content

X-ray technique was used for determination of residual strains and stresses. Corrundum

particles actually served as sensor for these measurements. Good precision in lattice

measurements (~110"4) was obtained. Lattice constants "a" and "c" of hexagonal

corrundum decreased with increase of particles amount in solution. At particle content

about 240 g/1 lattice constants approach those of the free powder. Residual strains in

direction normal to the sample surface were calculated as £2 - Ac/c, where Ac is reduction

of lattice constant (c). The value of £2 ~ 2-10"3. The further calculation of residual

stresses was based on AI2O3 particle location in three dimentional stress field.

It was revealed that residual stresses reduced as AI2O3 particle content increased and

current density dropped.

Wear behavior of composites is discussed in terms of their residual stress condition.

PI .32

QUANTITATIVE NON - DESTRUCTIVE LAYER - BY - LAYER ANALYSIS OF THE

SURFACE SUB - REGION OF SOLIDS BY EPMA

A. Berner

Dept. of Materials Engineering, Technion-Israel Institute of Technology, Haifa, Israel

A new method for non-destructive quantitative control of element content depth

distribution in submicron surface layer of solids has been developed. The method

consists in electron probe overvoltage variations for Electron Probe X- Ray Microanalysis

(EPMA) and measurements of characteristic X-ray radiation intensity. The connection

between the dependences of X-ray production I(E) and element content depth distribution

C(z) is define by an integral equation. The concentration depth profile C(z) can be

obtained by the measurement of I(E) and the solution of the given integral equation. The

correction method is based on a X-ray production depth distribution function derived

within the framework of the two-flux presentation of electron-solid interactions. The

main advantage of this approach is that without any extra assumptions or simplifications,

it can be effectively applied to a system with an arbitrary form of C(z).

The method allows for the determination of composition and thickness and of thin

submicron films on substrates and element depth distribution, in a non-destructive

manner. The thickness of analysed layers can be from 50 nm to several micrometers.

Depth resolution in layer-by-layer analysis may range from 8 to 80 nm. Errors of content

determination are equal to 5-10% rel.

The method was applied to the analysis of thin films of Si-Ge on Si substrates as well as

to element content depth distribution control in some amorphous alloys and ion doped

samples. The results obtained by this method are in good agreement with Auger Electron

Spectroscopy and Secondary Ion Mass Spectrometry results.

p 1 . 3 3

EDS AND X-RAY DIFFRACTION STUDY OF TERNARY ARTIFICIAL

SUPERLATTICES

I. Goldfarb, E. Zolotoyabko, A. Berner and D. Shechtman

Technion-Israel Institute of Technology, Haifa 32000, Israel

Artificial superlattice attract a great attention due to the possibility of "tailoring" unusual

properties on interfaces with reduced dimensionality. Applications were found in mirror

production for soft X-ray and ultraviolet radiations. The preparation of conventional flat

superlattices involves an alternating deposition of components providing control of layer

thickness on atomic level and absence of interdiffusion at the interfaces.

New advantages arise when wedge-layered superlattice are prepared. For example a set

of the samples with continuously varied concentration of the components can be produced

simultaneously. This set may be used in order to investigate various properties as well as

the phase diagram of multi-component systems.

Here we present the results of X-ray diffraction (XRD) and Energy Dispersive

Spectroscopy (EDS) of wedge-layered Au-Ag-Cu superlattice, produced by means of

magnetron-sputter deposition. EDS has been carried out with 5 KV accelerating voltage

using Au M Ag L and Cu L radiations. Quantitative results were obtained using

conventional ZAF correction and the observed compositions were compared to the

theoretically expected from the geometry of sputtering set-up. The correlation was rather

good, giving correlation factors 0.95-0.99.

X-ray diffraction patterns of all as-deposited samples revealed satellite-like structure of

(11 l)-peaks, providing an evidence of the composition-modulated artificial superlattice

formation. The experimental spectra are well described in a frameworks of kinematical

theory for imperfect superlattice.

The computer simulations have demonstrated extremely high sensitivity of the fitting

procedure to the fluctuations AH/H of the superlattice period H. As a result a rapid, non-

destructive and simple method of AH/H determination is proposed.

P I . 3 4

i

PREADHESION LASER SURFACE TREATMENT OF COMPOSITE POLYMER,

POLYMERS AND METALS ADHERENDS

M. Rotel*, J. Zahavi,* A. Buchman**, H. Doduik**

*Israel Institute of Metals, Technion City, Haifa 32000, Israel

••Materials and Processes Department, Rafael, P.O. Box 2250, Haifa 31021, Israel

Proper surface treatment of an adherend is among the decisive factors with respect to the

final quality and durability of an adhesive joints. Various surface treatments are practiced

for plastic and metals among them abrasive treatment, chemical treatment and plasma

etching.

Excimer laser surface treatment presents a new technology for preadhesion treatment of

various adherends such as aluminum alloys, thermoplastics and composite polymers.

This method presents an alternative for the use of ecologically unfriendly chemicals

involved in conventional pretreatments such as anodization and etching. Experimental

results indicate that preadhesion laser surface treatment improve significantly strength of

aluminum specimens bonded with rubber modified epoxy compared to untreated and

anodized substrates. Also adhesion shear strengths of Polycarbonate, polyetherimide and

composite adherends are improved compared to untreated or abrasive treated substrates.

Optimal laser parameters (intensity, number of pulses) depends on treated materials. The

mode of failure changes from adhesive to cohesive depending on laser parameters.

Morphology changes ans chemical modification are responsible for the improved

adhesion.

I

P I . 3 5

LASER PL ANARIZATION

S. Tamir, J. Zahavi*, Y. Lemer**

**National Semiconductors T.T.D, Migdal Haemek, Israel

Thin film interconnection technology is becoming very important as the density and speed

of semiconductor devices continue to increase. High speed signal propagation is achieved

by increasing film thickness and decreasing of line width. These demands lead to sever

step coverage problems over high aspect-ratio metal lines and viaes which result in a poor

electrical resistance and low reliability of the integrated circuit. One of the solution for

filling the viaes is a planarization process using a laser which operates in a pulse mode.

Laser irradiation of aluminum metal lines for a very short time cause to a local heating and

melting of the metal. The molten metal flows into the via and filled it with the metal.

In this work we studied the mechanism of via hole filling using an excimer laser operating

at a pulse mode. Pulse duration is 24 nsec and laser wavelength is 193 nm. The beam

was directed in perpendicular to a sample of chip which was obtained in its final stage of

production or after metallization and before etching. The specimens were irradiated in a

vacuum chamber at a total pressure of 1.5-10"6 Torr. The laser energy was concentrated

in order to increase the energy. Via holl filling was obtained at laser energy higher than

1 J/cm2 in both kind of specimens, however better results were found at irradiation of

chips which were in a stage after metallization before etching and patterning of the metal

lines. Quantitative analysis of the filled via showed that aluminum and silicon

concentration was the same as the aluminum matrix at laser energy range of 1.7 J/cm2

keeping the underlayer film not affected. Scanning Electron Microscope (SEM)

observations showed that the filled viaes were smooth but there were some morphology

changes in the aluminum metal. The details of results and mechanism of via hole filling

will be presented in the paper.

P I . 36

DURABILITY OF GLASS FB3RE REINFORCED CEMENTITIOUS COMPOSITES

WITH DIFFERENT LOW ALKALI / LOW LIME MATRICES

A. Bentur*, K. Kovler* and I. Odler**

•National Building Research Institute, Technion-Israel Institute of Technology, HaifaIsrael

**Technical University Clausthal, Germany

In recent years considerable effort has been directed at the research and development of

new glass fibre reinforced cement composites intended for replacement of asbestos-

cement, as well as to generate new materials of improved properties, in particular

toughness. However, due to the high surface area the fibres are sensitive to interfacial

effects with the matrix, which can be chemical or physical in nature and beneficial or

deterious from the durability point of view.

In the present work three low alkali/low lime cements were developed (Phosphate, Glass

and Aluminum Phosphate cements), which have the potential for providing high

durability composite. The ageing performance of composites of these matrices,

reinforced with E-glass fibres, was studied.

The considerable difference in the ageing performance of E-glass composites with

different cementitious matrices could be observed and accounted for on the basis of

microstructural and chemical effects. In the case where chemical attack and

microstructural densening was eliminated (Phosphate cement composite), loss in

microstructural densening was eliminated. In composites where the chemical attack was

severe (Portland cement) and compounded with microstructural densening (Aluminum

Phosphate cement), the durability performance was poor. In the case the Glass cement

composite, where microstructural densening was eliminated and the chemical attack was

rather mild, the loss in mechanical properties over ageing might be considered as

tolerable.

These results clearly prove the hypothesis that by adjusting the composition of the matrix,

there is a potential for developing high durability fibre cement composites.

P I . 37

(j C O R R O S I O N A N D S T R E S S C O R R O S I O N C R A C K I N G B E H A V I O R O F AISI 304

I A N D AISI 3 1 6 STAINLESS S T E E L S I N 5 5 % LiBr

t< Ofira Elias*, Irit Lev*, David Itehak* and Pnina Peled**II *Department of Materials Engineering, Ben Gurion University of the Negev,f Beer Sheva, Israel

**The Bromine Compounds Ltd., Israel

The corrosion and stress corrosion cracking (SCC) behavior, of AISI 304 and AISI 316

stainless steel in LiBr environments, was investigated.

U-bend tests, constant load tests, potentiodynamic polarization and open circuit potential

measurements, were performed. The experiments were carried out in 55% LiBr

environment at temperatures of 60-140'C and pH ranging from 6 to 11.6.

It was found that AISI 304 and AISI 316 stainless steels are sensitive to SCC in 55%

LiBr environment at temperatures higher than 80°C within the pH ranges of 6-11.6. AISI

316 shows higher resistance to SCC in this environment.

Transgranular fracture was observed in the constant load tests, exhibit transgranular and

ductile fracture, while AISI 316 failed in a mixed transgranular -»intergranular —> ductile

fracture. Both stainless steels exhibit active passive behavior in the tested environments.

PI. 38

THE INFLUENCE OF ELECTRON IRRADIATION ON ADHESION OF METAL

FILMS

Sara Stolyarova

ELTAM Technology Inc. Ltd., P.B. Box 600, Haifa 31000, Israel

The effect of electron irradiation on the adhesion of silver and copper films to vacuum-

cleaved LiF and silica-based glass substrates have been investigated.

The samples were exposed to high energy pulse irradiation: E = 3.5 MeV, f = 1.72 Hz,the density of electrons per pulse - 7-109 el/cm2. Doses varied from 1012 to 1010 el/cm2

(102- 109 pulses).

The films 350 nm thick were deposited by thermal evaporation. The adhesion strength

was measured by direct technique. Fracture surfaces were studied by the use of

transmission electron microscope.

Three schemes of experiment were used. The first scheme served to reveal the role of

type and density of point defects created in substrates by electron irradiation. For this

purpose the substrates were irradiate throughout, the bulk density of point defects was

measured by spectrophotometer and after that the substrates were cleaved in vacuum

directly in metal vapor stream. The fresh, free from contaminants contact of the metal

film with the surface enriched with point defects was formed in this way.

The nonmonotonous dependence of the adhesion strength on the irradiation dose was

observed for both types of substrates. It was shown that the formation of simple point

defects (F-centers) in the substrate enhances the adhesion of the films whereas the

appearance of defect aggregates leads to adhesion failure at high irradiation doses.

The second experimental scheme included direct irradiation of substrate surface in air

before film deposition and allowed to study the effect of radiation induced chemical

reactions with the environment on the adhesion strength. This kind of treatment has

shown opposite effects in LiF and glass. The adhesion strength of silver film on LiF

dropped while that in glass substrate increased significantly.

In the third scheme the irradiation of the already prepared film-substrate contacts was

studied. In this case the irradiation led to adhesion failure of Ag films both for LiF and

glass substrates due to blistering effects ans reaction product formation at the interface.

Basing on this studies the optimal conditions for adhesion activation have been found and

the physical models for the effects observed have been proposed.

THE EFFECT OF FREQUENCY IN PLASMA MATERIALS PROCESSING

A. Raven*. A. Bettelheim**, J.E. Klemberg-Sapieha**, L. Martinu** andM.R. Wertheimer**

*NRC-Negev, Division of Chemistry, P.O. Box 9001, Beer Sheva 84190, Israel

**"Groupe des Couches Minces" (GCM) and Department of Engineering Physics, EscolePolytechnique, Box 6079, Station "A", Montreal, Quebec H3C 3A7, Canada

The advantages of low pressure plasma over conventional processing techniques are well

known. In view of certain distinct advantages of "high" frequency (microwave,

2.45 GHz) than "low" frequency (0.5 or 13.56 MHz), two particular material

processings were studied [1-3]: (i) surface nitriding of a/(3 titanium alloy by nitrogen or

by a nitrogen mixture with hydrogen, and/or argon, (ii) deposition of diamond-like

carbon (DLC) in methane, methane-argon or methane/hydrogen mixtures.

It is shown that "high" frequency plasma affects in more pronounced way the

fragmentation and the creation of more species with high excitation potentials than the

"low" frequency, as well as the characteristic microstructure, composition and formation

rate. For the nitriding process, it was observed that nitriding of Ti-6A1-4V (a + P

structure) at higher frequency increases the phase content of e and a ' phases and

decreases the 8-phase content. Nitriding of Ti-8Al-lV-lMo (a structure) at higher

frequency result in an increase of a'-phase content and a decrease of e-phase content;

whereas the 8-phase content remains constant. For the deposition of DLC, it was

observed that the higher frequency results in more hydrogen bonded to the films with a

higher deposition rate; whereas, ion bombardment at the surface enhances reactions in the

gas phase and results in hard (about 30-48 GPa), low stress (about 0.5 GPa), and thick

3-10 |im) films containing 20-30 at.% of hydrogen.

The effects of the plasma excitation frequency on processes in the plasma bulk and on the

structure and properties (phase formation, formation rate, lattice parameters, hardness,

wear and density) of the nitrided layers and of DLC films are presented and discussed.

1. A. Raveh, G. Kimmel, R. Avni and A. Grill, Advances in X-Ray Analysis 13,

(1990) 129-135.

2. A. Raveh, R. Avni and A. Grill, Thin Solid Films 186, (1990)241-256.

s3. A. Raveh, L. Martinu, J.E. Klemberg-Sapieha, and M.R. Wertheimer. J. Vac. ;j

Sci. Technol. A10, (1992) 1723-1727. $

P! . 4 0

THE POSSIBLE USE OF MIXED IONIC ELECTRONIC CONDUCTORS, INSTEAD

OF ELECTROLYTES, IN FUEL CELLS

I. Riess, Physics Department, Technion IIT, Haifa 32000, Israel

Mixed ionic electronic conductors (MIECs) are considered for replacing pure ionic

conductors i.e. solid electrolytes (SEs) in fuel cells (FC)'. It is shown that an electronic

conductivity that originates from a change in stoichiometry under reducing or oxidizing

conditions at th electrodes, can be tolerated provided the FC is operated close to its

maximum power output. Thus a MIEC can replace a SE in a FC that is intended to

operate under those conditions.

The operating conditions in the electrolysis process of water are different. Under these

conditions MIEC cannot replace a SE.

The analysis leading to the acceptance of mixed conductivity suggests also that electrodes

can be prepared by stoichiometry or by doping of the surface region of the SE or MIEC

used. The stoichiometry change and the doping will turn the surface regions into

semiconductors which can serve as electrodes.

The use of a protective thin SE layer on a MIEC is analyzed. It is not needed for a FC

operated under maximum power output condition. It may, however, be useful for low

power operation conditions and for electrolysis.

1. I. Riess, Solid State Ionics 52 (1992) 127.

PI .41

FRACTURE OF CARBON FIBRE REINFORCED PEEK UNDER STATIC ANDFATIGUE CONDITIONS: THE INFLUENCE OF THE DEGREE OF CRYSTALLINITY *

A. Tregub*, H. Harel*. G. Marom* and C. Migliaresi**

*Casali Institute of Appl, Chemistry, Graduate School of Appl. Science and Technology,The Hebrew University of Jerusalem, Jerusalem 91904, Israel

**Dept. of Materials Engineering, Univ. of Trento, Mesiano 38050, Trento, Italy

Recently, our results of a study on the effect of the degree of crystallinity on the

mechanical properties and fatigue behaviour of poly(etheretherketon) (PEEK) matrix

composites have been reported. That study compared the mechanical behaviour of

samples with low (10%) or high (35%) degree of matrix crystallinity, and for different 4

loading angles with respect to the reinforcement direction. It was shown that the degree

of crystallinity effect was not confined to matrix dominant loading directions. Rather, %

unexpected improvements with increasing crystallinity were observed in the mechanical

strength and modulus and in the fatigue life, for fiber governed longitudinal samples.

That effect was attributed to the influence of a transcrystalline layer, presumably formed

on the fiber surface. It has been shown before that a transcrystalline layer could affect the

stress transfer mechanism and reduce the residual thermal stresses. Thereby, its presence •*

could improve certain longitudinal mechanical properties.

The present study reports the results of a fractographic study performed in order to check

the hypothesis on the effect of the transcrystalline layer. For that, the fracture surfaces of h :

carbon fibre reinforced PEEK composites (APC-2) samples, failed either statically or by

fatigue loading, were studied. The emphasis was laid on the question of how the

presence of the transcrystalline interlayer results in a transition from an adhesive failure at . J

the fibre/matrix interface to a cohesive failure within the interlayer.

The fracture surfaces of longitudinal and transverse specimens of two levels of

crystallinity, namely, of the as received material (35%) and of a thermally treated

quenched material (10%), after static, fatigue and impact 3-point bending, were studied »

by scanning electron microscopy. The fractography revealed different extents of matrix j, -

material adhered to the fiber surfaces, depending on the degree of crystallinity and on the

testing mode. In general, however, the fibres in the fracture surfaces of the lower fci

crystallinity materials were mostly exposed, whereas those of the higher crystallinity p\

materials were covered by matrix debris bonded to the fibre surfaces. The presence of '

matrix fragments on the fibres implies that in the higher crystallinity material the fibre j

forms a stronger bond with the matrix, probably through a transcrystalline interlayer, ~

within which fracture ultimately occurs. The paper discusses the mechanical strength, the

fatigue behaviour and the fracture properties of the composites in terms of specific

potential contributions of the transcrystalline interlayer. 1. \

PI . 4 2

RAPID THERMAL ANNEALING OF HIGH DOSE ARSENIC-IMPLANED SILICON

E.N. Shauly* ** and Y. Komem**

•Department of Diffusion/Ion Implantation - National Semiconductor - Migdal Ha'Emek,10556, Israel.

**Department of Materials Engineering, Technion, Haifa, Israel.

A scaled CMOS technology requires shallow source and drain (s/d) junctions. Junctions

depths for 0.5 \x CMOS technology are approaching 100 nai or less, to prevent

punchthrough and short channel effect for the N+/p s/d regions. Rapid Thermal

Annealing (RTA) provides a promising technique to minimize the displacement of ion

implantation impurities while activating impurities and annealing implantation damage.

In this work the effect of RTA on the diffusion, activation and clustering was studied in

(100)Si after implantation at different doses by resistivity measurements (Rs), Secondary

Ion Mass Spectroscopy (SIMS), and by Spreading Resistance Analysis (SRP). The

ranges of the implants doses was 3.29 x 1015 to 8.20 x 1015 [cm"2] with energy of

60 KeV. The RTA temperatures were between 980c and 1200c and times from 1 to 300

sec. For comparison hot-wall furnace annealings were performed at 900c and 550c for

2h and 30 min respectively. A computer model was developed to predict the maximum

activation of the electrically active implants.

The effect of implantation dose, the RTA time, and the RTA temperature at different

conditions, was compared with the computer modeling. It was found that for the RTA

higher does leads to lower Rs and deeper junction depth (Xj). However, after hot wall

furnace annealing higher dose led to higher Rs. Longer RTA time decreased the Rs and

increased Xj. Higher temperature improved the Rs due to less clustering effects.

The work was sponsored by National Semiconductor, Migdal Ha'Emek, Israel.

•fi

CHARACTERIZATION OF THE IMPLANT ENERGY DISTRIBUTION OF HIGHCURRENT BF2 IMPLANTS INTO (001) Si

N. Bacharach**, E.N. Shauly* **, Y. Komem** and Y. Avrahamov*

*Department of Diffusion/Ion Implantation - National Semiconductor - Migdal Ha'Emek,10556, Israel.

**Department of Materials Engineering, Technion, Haifa, Israel.

In the fabrication of p+/n-junctions in CMOS application, the use of BF2 as the implanted

species instead of boron has become very common. The additional fluorine causes the

amorphization of the implanted silicon substrate. When the implanted specie is boron,

there is no amorphization. Amorphization reduces channeling effects and enabling

shallower junctions for demand of higher gate densities.

BF2 has been implanted using a high current implanter into (001)Si substrate. The

implant does was in the range 3-4.3 x 1015. Different acceleration and extraction voltage

ratios were used. Some of the implanted samples were annealed using Rapid Thermal

Annealing (at one step at 1100c or two steps of 600c + 100c) and others were annealed

in a hot-wall tube (at one step at 950c or two steps at 550 + 950c). The profiles of the

fluorine and boron were measured by SIMS after implantation and after annealing

treatments. Sheer resistance was measured after annealing.

It was found that dissociation of BF2 ions occur during implant. The dissociation effect

increases as the ratio extraction/acceleration voltage decreases. The dissociation level

were calculated for different ratios. The effect of the ratio on the sheet resistance were

also studied.

The work was sponsored by National Semiconductor, Migdal Ha'Emek, Israel.

f

A COMPARISON OF TCA (TRICHLOROATHANE) AND DCE (TRANS 1,2DICHLOROETHLENE) - GROWN OXIDES ON SILICON

E.N. Shauly* **, R. Mor* and Y. Avrahamov*

*Department of Diffusion/Ion Implantation - National Semiconductor - Migdal Ha'Emek,10556, Israel.

**Department of Materials Engineering, Technion, Haifa, Israel.

In most VLSI processes, chlorine is introduced into the oxidation ambient to improve

both the oxide and the underlying Si properties. The most popular chlorine sources are

HCI, TCE or TCA. TCA has recently been identified as an ozone depleting chemical

since it is very stable, and DCE was proposed as an alternative. DCE and HCI are

substitute chemicals for TCA, but DCE is superior in performance to corrosive HCI.

Process change from TCA to DCE need full checking of the process kinetics as well as

the device characteristics.

A comparison of TCA and DCE was made considering the following aspects: oxidation

rate for the growth of thin oxides (<350A) using Nicollian-Reisman power law, oxide

thickness for all CMOS oxidation processes, fixed oxide charge Qf, mobile ionic charge

Qm , and C-V shifts for 1000A oxide. Breakdown voltage, leakage current, life time

evaluation and yield results were compared using capacitors, SRAM and Answering

Machine micro-processor using 1.0 Ji CMOS (Twin Well) technology that ran with TCA

or DCE.

It was found that oxidation rate with TCA and DCE have the same Nicollian-Reisman

kinetics constants. All the CMOS processes grew the same thickness (within 3a). The

C-V results show the same Qm levels where the average Qf is 35% less for the DCE

oxide. Breakdown voltage, leakage current, life time evaluation tests and yield were

comparable for the two chlorine sources.

The work was sponsored by National Semiconductor, Migdal Ha'Emek, Israel.

PI . 4 5

INVESTIGATION OF THE ACOUSTIC FIELD GENERATED BY REACTIVE SPUTTERED

ZnO LAYERS IN ACOUSTO-OPTIC DEVICES, BY MEANS OF X-RAY DIFFRACTION

E. Jacobsohn. E. Zolotoyabko and D. Shechtman

Dept. of Materials Engineering, Technion-I.I.T., Haifa 23000, Israel.

ZnO films have aroused increasing interest lately due to their potential use in electrooptic

and acoustooptic devices.

There is a growing interest in using the silicon as a substrate since silicon technologies are

highly developed. The advantage of such a use is in the possibility of integrating

electrooptic and electronic devices on a common substrate.

In the current investigation ZnO (1 |*m in thickness) was reactively sputtered on top of an

SiO2 layer by dc magnetron gun. The films were deposited at power levels ranging from

100 to 250W. The gas mixture contained O2 with partial volume ranging from 20% to

80% at total pressure of 3-10 mtorr.

The influence of the deposition parameters on the structure orientation and stoichiometry

of the ZnO film was determined by means of AES, XRD, SEM and TEM.

It was found that the O2 partial pressure has a crucial effect on the microstructure

crystallographic orientation and stoichiometric properties of the ZnO film.

SAW devices were then made. The acoustic field of the devices were studied by electrical

measurements as well as by means of in situ X-ray diffraction. A new approach for

probing acoustic field in acousto-opti'cal devices based on dynamical X-ray diffraction is

demonstrated. The experimental results as well as the advantages of the method are

discussed.

PI. 4b

f' IN SITU X-RAY DIFFRACTION DURING THE FORMATION OF TiSi2 C49K FROM Ti-Si MULTILAYER ON Si(100)

d?, J. Sariel* and H. Chen**

* *Nuclear Research Center Negev, POB 9001, Beer-Sheva 84190, Israel.

', **University of Illinois at Urbana Champaign, Dept. of Mat. Sci. and Eng.,; 1304 W. Green St., Urbana, IL 61801, USA.

Si and Ti multilayers transform at high temperatures (above 700°C) to TiSi2-C54. Thisphase is important for microelectronic applications because of its low resistivity, stabilityup to 900°C and compatibility with silicon processing. However before this phase isformed, an unfavourable metastable TiSi2-C49 phase is already formed at lowertemperature.

The kinetics of the transformation of TiSi2-C49 phase can be characterized as a process ofnucleation and growth, using the well known Johnson Mehl Avrami (JMA) equation:

f = 1 - exp (-ktn)

where k - the rate constantt - the reaction timen - Avrami exponent

In the present work the transformation of a multilayer of Si and Ti to the C49 phase isstudied by in situ X-ray diffraction. Isothermal annealing in vacuum was done at fourdifferent temperatures, 2 7 0 ^ , 290oC, 300°C and 310°C. A position sensitive detector(PSD) was used to collect the diffracted beams of (060) and (131) peaks, during theannealing time. From the plots of Ln(Ln(l/(I-f))) as a function of Ln(t), for eachtemperature, the Avrami exponent, n, was determined:

n = 2.0 ± 0.1

The rate constant, k, is a function of the temperature, according to the equation:

k = k0 - exp (-Q/RT)

where ko - pre exponentQ - activation energy

•( R -gas constantT - temperature

By measuring the transformation isothermally at several temperatures, deriving k at eachtemperature and drawing Ln(k) as a function of 1/T the activation energy of thetransformation, Q, was found to be:

Q = 2.5 eV

These values of Q and n were comparable to the values found by others in the literature.

f

PI . 4 7

PREDICTION AND CALCULATION THE PROPERTIES OF CERAMICS WITHSPINEL STRUCTURE

E.N. Men, I. Sinitsky and D.G. Brandon

Department of Materials Engineering, Technion, Haifa, Israel.

A self-consistent phenomenological scheme (CCM - cluster component method) has been

used to describe and predict the crystal chemical and magnetic properties of defect spinels

and solid solutions.

The central idea of CCM is the relation of structure (including point defects and short and

long-range order parameters) with a set of material properties by decomposition of the

given solution into its components on the basis of suitable ordered structures in the given

lattice.

A simple defect spinel y - M2O3 and its solid solutions

(1-C) MgQVi/304-c MM2O4

are considered (M1 = Mg, Fe, Zn1 M = Al, Cr, Fc).

The influence of composition, defect content, degree of order and partial pressure on the

lattice parameters and magnetic properties these spinels was investigated.

PI. 48

T

S ;-l THE SYNERGICTIC EFFECT OF ENVIRONMENTAL PARAMETERS ON THE

i '•! BEHAVIOR OF PLASTIC MATERIAL

* R. Huberman, E. Gutman and D. Itzhak

Dept. of Materials Engineering, Ben Gurion University of the Negev, Beer Sheva, Israel

The behavior of PMMA (Polymethyl methacrylate) and SAN [the random copolymer ofstyrene (70%) - acrylonitrile (30%)] in water saturated atmosphere under UV irradiation at80°C was studied.

The samples were exposed to the aggressive environments for about 4000 hours. The

exposed samples were mechanically and optically tested.

It was found that SAN is more stable as compared to PMMA and can be used as glazingmaterials for the cover of the Heliocol sun light collectors.

PI.49

THE EFFECTS OF DOPANTS ON THE DEVELOPMENT OF THE

MICROSTRUCTURE IN THIN FILMS OF AI2O3

W.D. Kaplan and D.G. Brandon

Dept. of Materials Engineering, Technion-Israel Institute of Technology, Haifa, Israel

In order to study the structure of general grain boundaries in alumina, doped and undoped

anodic films of alumina were grown on aluminium substrates. The films are produced by

the anodization of aluminium in a doped or undoped electrolyte, removal of the

amorphous film from the metal substrate, and the subsequent crystallization of the self-

supporting sample on specially prepared TEM sample grids. Films of a thickness of the

order of 5 nm to 50 nm can be produced. Doping of the anodic films was achieved by

adding cations of the desired dopant element to the anodizing electrolyte. The

crystallization of the thin films is achieved through heat treatment in air at various

temperatures. Above 1250°C, the (X-AI2O3 structure forms, and this was the main phase

studied in this work.

The purpose of the films was to provide high quality specimens for grain boundary

characterization by high resolution electron microscopy (HREM) due to the large number

of grain boundaries, and their near-normal orientation to the film surface. However, the

introduction of different dopant elements caused changes in the microstructure of the film.

These changes include grain size, degree of porosity, faceting of pores and grain

boundaries, and changes of the film thickness during the crystallization process. In some

cases, the average grain size was found to exceed the film thickness by an order of

magnitude.

The limitations and possibilities of this sample preparation technique will be presented, as

well as preliminary characterization of the dopant-affected microstructure.

P I . 50

MICROSTRUCTURAL EVALUATION OF ALIGNED CERAMIC MATRIX

COMPOSITES

N. Shafry, D.G. Brandon

Dept. of Materials Engineering, Technion-Israel Institute of Technology, Haifa, Israel

The microstructure of a ceramic composite was quantitatively characterized in order to :

determine numerical values for the microstructural parameters which affect the interfacial :

shear stress. The fiber diameter and the spatial fiber distribution were determined to

characterize the degree of order of the fibers within the composite. ',

The material for these studies was a 2-dimensional, SiC fiber-reinforced, glass-ceramic &

laminate. .

The specimens were polished, optically micrographed, and then lapped and repolished \

and micrographed again, taking the same location to produce a serial section. This •;procedure was repeated for each specimen, removing 25 to 50 |im at each stage. '

The micrographs were digitized using a Macintosh "OneScanner" and image analysis was

performed using "Image 1.44" software. Each micrograph, containing over 100 fibers,

was analyzed to obtain the diameter of the fibers and their center coordinates. Basic

statistics were used to compare the data for single identified fibers through the serial

sections and the angle of deviation of the fibers from the direction to the slicing was

determined. The results show significant misalignment of the fibers within the

composite, as well as other sources of stochastic deviation from ideal architecture.

P I . 5 3

I

A COMPUTER PROGRAM FOR THE CALCULATION OF ATOMIC POSITIONS ON

GENERAL GRABS BOUNDARIES

W.D. Kaplan and D.G. Brandon

Dept. of Materials Engineering, Technion-Israel Institute of Technology, Haifa, Israel

The influence of grain boundaries on the characteristics of polycrystalline materials is

important, both from a technological and a scientific point of view. With recent increases

in the resolution of high resolution transmission electron microscopes (HRTEM), there

has been a marked increase in the number of scientific research programs on the atomic

structure of grain boundaries.

However, computer simulations of the image must be conducted to understand the

HRTEM images. These simulations involve the combination of the crystal (or defect)

potential with the contrast transfer function (CTF) of the HRTEM.

While a number of computer programs for the simulation of HRTEM images exist, most

of these software routines include only the generation of ideal periodic crystallographic

structures. The initial determination of atomic positions at defects, such as grain

boundaries, requires computer codes of a different nature, which allow for rotation,

translation, and varying occupancy over different regions of the crystals to be studied.

In order to fulfill these requirements, a computer program has been developed which

generates general grain boundaries. The program operates through conversion of the

general Bravais symmetry to orthonormal space, and the generation of large simulated

bicrystals. (The large size of the bicrystal has been set to minimize edge-effects in the

subsequent image simulation programs). The program runs on personal computers, both

IBM-PC and Apple Macintosh, and prepares super-cell files in EMS format.

Possible uses and limitations of the software program will be presented, as well as a

number of examples.

P I . 5 2

STRONG ELECTROSORPTION AT THE THIN BISMUTH FILM / ELECTROLYTE

INTERFACE

A. Bluvstein

Advanced Technologies Center, TEMED Industrial Park, 206 Oron Rd,

Arava, 86800, Israel

Thin bismuth films are relatively new object in electrochemistry. Recently a number of

peculiar effects were found at the thin Bi film/electrolyte interface. Surface conductance

(SC) vs electrode potential curve qualitatively corresponds to that of semiconductor

electrode with minimum at positive charge of the surface. At the negative charges SC can

be described quantitatively by the fields effect. At the positive surface charges the SC

increase is caused by oxygen electrosorption (for non-adsorbing electrolyte) or by halide

chemisorption in the presence of Cl", Br' and I". Besides, halide adsorption results in the

negative shift of the minimum of SC vs potential curve, and partial charge transfer upon

adsorption rises in series Cl" < Br" < I".

Time-resolved SC measurements show that adsorption kinetics obeys the Roginskii-

Zeldovich equation. The kinetic parameters are also calculated. It is supposed that SC

rise is connected with hole injection into the space charge region of Bi thin film electrode

by surface states formed upon oxygen and halide adsorption.

PI.53

A METHOD FOR THE MEASUREMENT OF THE THERMAL CONDUCTIVITY C'

j TENSOR IN THEM LAYERS OF YBa2Cu3O7

* L. Kornblit, N. Gluzman, M. Auslander

* Ben Gurion University of the Negev, Beer Sheva, Israel "

A plate of MgO (10 x 5 x 0.5 mm3) is used as a substrate on which is grown a layer of

YBa2Cu3O7 0.5 \im thick. The layer of Ba2Cu3O7 is covered with a film of SrTiO3 which

must be about 0.005 ^m thick. On this film are vapour deposited a heater/thermometer

and a thermometer in the form of two narrow (~ 3 nm) silver strips (thickness 0.3 Jim, :

length 2.5 mm) with branches for current and potential probes. The SrTiO3 film isolates

the heater/thermometer and the thermometer from the YBa2Cu3O7 layer. •}'•i

Calculations show that the components of the thermal conductivity tensor A* (within the

thin layer) and X.y (the component in the direction perpendicular to the plane of the layer

can be found with the accuracy of ± 5%.

P2.1

STRUCTURE OF TiNx NITROGEN RICH FILMS

Rafael R. Manory* and Giora Kimmel**

•Department of Chemical and Metallurgical Engineering and Microelectronics andMaterials Electronic Center, RMIT, POB 2476V, Melbourne, Vic 3001, Australia

**Division of R&D N.R.C.N/, POB 9001, Beer Sheva 84190, Israel

This paper discusses various defects in TiN and related nitrides and their repair by heat

treatments. TiNx thin film received on glass by reactive sputtering under various

conditions. X-ray diffraction showed gradual structural changes as a function of the

amount of nitrogen. It was clear that the strongest diffraction line was (200) for lower

nitrogen contents and (111) for overstoichiometric cases. The structure was imperfect.

After heat treatment an almost perfect NaCl structure was formed.

P2.2

XRD INVESTIGATION OF CHROMIUM ALLOYED MEDIUM CARBON STEEL

X-20 CrMoV12.1

M. Yelin*, P. Yoffe*, S. Libov**

*IEC- Materials Laboratory, Haifa

**Technion, Haifa

Steel X-20 CrMoV12.1 was investigated as a promising heat resistant material. The

investigated steel specimen contained 0.18% C, 10.5% Cr, 0.25% V, 0.9% Mo, 0.6%

Mn, present as probable carbide generators, with the addition of 0.8% Ni. The steel was

investigated at the following states:

1. as received (AR);

2. rolled with up to 30% reduction at 720°C (R);

3. heated at 600°c for 125 hours and coo/ed in air (HT);

4. after high temperature creep testing at 600°C under 20kg/mm^ load (HTC);

5. after exposing during 20 minutes at 1200°, 1250°, 1300°, 135O°C.

Lattice strain (LSt) values. Lattice size changes (LSi), Austenite presence and Carbides

transformation (CT) were examined and considered. ASTM Data Base was used for

phase analyses. a-Iron analytic line width and broadening were measured for lattice

parameters. Strain evaluations were made from comparison between XRD spectra for AR

sample and the others. The following phase composition peculiarities were obtained:

1. Austenite was not revealed at XRD level for HTC and " 1350" states.

2. All of other states had 1.5-3% vol. austenite present.

3. Dominant kinds of carbides were M23C6 for AR and M7C3 for all other states.

4. The total freo carbide amount is minimum at R state and maximum at "1250".

5. Heating up to t > 1250°C results in Fe-Cr and/or Fe Cr Mo intermetallic compounds.

6. The largest LSt value was 0.303% (Sample "1200"), and the smallest one 0.08%

(HTC specimen).

A comparison between phase analysis and lattice parameter changes brings one to the

conclusion that precipitation of intermetallics ought to unload the matrix twice as small on

a micro-strain level. The carbide transformation kinetics model is offered and discussed

from the XRD and from the results (of other investigations).

P 2 . 4

H YDRCXJEN CONDITION IN MIDDLE CARBON LOW ALLOY BAINITE STEEL:

LOCALIZATION, DIFFUSION AND FLAKES GENERATION IN LARGE FORGING

Pavel Yoffe

Israel Electric Corp. Ltd., Haifa, Israel

The common point of view for Hydrogen condition (HC) in steel is absent, and H-Mechemical bonding for 3d-transitive metals is discussed as ls-4s and ls-3d hybridizativeINTERACTIONS impossibility at steel making conditions.

Energy of H diffusion activation (EAHD) was evaluated at 673K, 973K and 1273K andevaluation results were considerable to show at three types of snares as vacancies, freegrain surfaces as threevacancies.

The HC notion as free monoatomic flow was adopted and hydrogen embrittlementidea was used for flakes generation description as follows.

From called approximation and experiment condition the Fick's equation was decides asintegral which was equal to reduced mass of hydrogen. Bymodal form of curves showsthat two forms of H were extracted. The literature data of diffusion constants for Fe a

and Fe X were used, and for every form Eda were calculated (kcal/g at): 673K - 3.35 and2.84. 923K - 3.25, 2.84 and 5.45; 1273K - 5.5 and 7.0. The diffusion of two hydrogenforms - unbounced and absorbed by indented atoms - were fixed after comparison famousdata and ours. Experiments temperatures and forging cooling condition conformity let toconsider the FG next two processes collaborations contemporary:

1. Natural cavity filling by hydrogen up to CRITICAL pressure value (Pc) andsuperfilling of cavity - "in collector" diffusion (Die).

2. Cavity environment filling by hydrogen up to equilibrium solubility because ofopposite (out of collector) diffusion (Doc). The Die reason is concentration gradientand Doc's one - the back osmose, or surplus gas PRESSURE. When Pc > o w p orwhen forging is under abroad load cavity environment might be cracked up to lengthdetermined by diffusion way value. The last is snares concentration function and itsasymmetry lead to a trim asymmetry.

The local hydrogen concentration values were computed from real defects measurementsby an equation which let to estimate crack length dislocation density1 = (2.2-109 [H]/d(Ty), where - dislocation density, av - yield point and [H] - hydrogenconcentration. The last value relates to domestic (regional) condition and being computedfor our results gave data which were in a good accordance OF local mass spectrometry. Itis clear of course the local hydrogen embrittlement is probable as a result of hydrogenconcentration fluctuation, and crack trim should generate after outer loading. Activationenergy of H diffusion calculations and well known data show that during usualtechnological heatings of investigated steel forging the vacancies left by H at 673K, thefree surface - at 973K and threevacancies - at 1273K. The last defects part is not bedetermining because forged steel has high density as a rule.

P2.5

I A NEW METHOD FOR DETERMINATION OF HEAT TRANSFER COEFFICIENTS

| IN THE PROCESS OF RAPID QUENCHING OF AMORPHOUS METALLIC

f RIBBONS

| V. Manov*, M. Geller* E. Broyk-Levinson*, A. Manuchin**}•

*Department of Materials Engineering, Technion, Haifa, Israel

**Urals Polytechnical Institute, Ekaterinburg, Russia

Knowing cooling rate values is of great importance in the rapid quenching technology.

Rates of quenching are determined by the heat transfer coefficient between the melt and

spinning drum surface during melt spinning procedure. Measuring the temperatures in

the melt-drum system is complicated by the great value of the cooling rate (106 K/s).

• — A new method for temperature control of rapid quenched melts has been developed. The

method is based on the substitution of the real melt spinning procedure by the model one.

The model presents a double-layered system with the copper film deposited over the

amorphous one by the vacuum evaporation method. The heating of the double layer

system is realised by short high-power electrical pulse (1-2 mks). Due to great difference

between the two layer resistances, a significant difference arises between the temperatures

of the amorphous and copper films. Quartz thin films were deposited on both sides of the

| layered system to prevent its oxidation during the rapid heating and cooling. High

sensitive photoelements are used for temperature measurements.

. s The experimental data are obtained by using the oscillograph and are treated by the

^ equation of heat balance between amorphous film and copper. As was revealed, the value

of heat-transfer coefficient is 5-104 W/m2K in the system Fe80 - B20 - Cu, that correlated

to melt spinning parameters for above mentioned system.

Suggested method of the heat transfer coefficients determination can be succesfully used

in the production technology of a new amorphous metallic alloys.

P2.7

PECULIARITIES OF GLASS-FORMING CONDITIONS OF INORGANIC,CHALCOGENIDIC AND METALLIC GLASSES

V. Manov, D. Shechtman

Department of Materials Engineering, Technion, Haifa, Israel

Peculiarities of glass-forming of inorganic, chalcogenidic and metallic liquids have been

analyzed. Experimental data concerning the structure of liquid and glasses, politerms of

viscous flow of glass-forming, values of liquidus temperature TL and vitrification

temperature Tg enables the extention of general principles of polymer structure of typical

glasses to metallic glasses. The formula for theoretical estimation of the vitrification

temperature has been obtained:

(EL + 2 0 R T L ) E L T L

(EL + 20RTL)EL + (EL - RTL)RTLlnf

where: EL - activation energy of viscous flow of liquids,

- . TL - melting temperature, 1012 Pas - vitrification viscosity value.

, . As have been shown for different glasses, the deviation of T g °r values from

experimental data less then 30K.

Conclusion. Correlation between glass-forming principles of inorganic, chalcogenidic

\*> and metallic alloys have been carried out. The method of definition of new metallic

glasses compositions on base viscous flow values of melts have been suggested and

tested succesfully.

P2.8

HYDR(XJEN ATTACK ON COPPER AND COPPER-BERYLLIUM ALLOY

SURFACE

D. Moreno* and D. Eliezer**

*NRCN, Beer Sheva, Israel

**Department of Materials Engineering, Beer Sheva, Israel

The importance of the interaction of hydrogen with metals, alloys and intermetalliccompounds in the field of nuclear reactors, permanent magnets, heterogeneous catalysis,powder metallurgy, electrochemical cells etc., has been the subject of considerableresearch (1-4). The nature of the sample surface and structure, the degree of oxidationand the ease of the chemical reaction in a specific environment, all vary markedly withdifferent materials. Surface interaction is the basic step of degradation in hostileenvironments like hydrogen, and it is known that the equilibrium surface compositionoften differs from their bulk in most alloys. Copper and its alloys tend not to formhydrides easily and therefore suitable for use in hydrogen environments. Copper'shydride is very rare (stable only in aqueous solutions), and has a FCC structure which ischaracterized by very low diffusivity hence the interaction with hydrogen is restrictedmainly to the surface. The technical preparation and irradiation procedure for the copperand copper beryllium samples have been reported elsewhere (5-7). A scanning electronmicroscope was used to determine the surface degradation on the samples. The exposedsurface of the charged copper samples revealed different types of degradation dependanton the surface history of the material. The degradation of the sample surface is duemainly to the traces of surface contamination which were coherent with the originalsurface structure. These traces are mainly the oxides, CuO and CuO2, and surfaceanalysis (Auger) has determined these oxides to be a few nm deep. The enthalpies of

formation for CuO and CuO2 are AHf = - 155.2 kJ/mol. and - 166.7 kJ/mol.,respectively. These oxides are most probably created during the production of thematerial, and during charging and dissociation of hydrogen near the copper surface, themost probable reaction is the formation of H2O as in the following reaction:

H 2 - >2HCuO + 2H > Cu + H2Oor CU2O >Cu2 + H2O

These spontaneous reactions are due to a lowering in the energy, as the enthalpy offormation of one mole of water is - 285.9 kJ/mol, significantly lower than either of thecopper oxides. The water formed during the reaction is added to the electrolyte solutionwhile holes and pitting are created on the surface. This reaction does not occur in thecopper-beryllium alloy since the beryllium reacts with the oxygen with an enthalpy offormation of - 610.9 kJ/mol, resulting in a very stable oxide and the surface is notattacked. In copper and copper alloys, the degradation is attributed ti the chemicalpotential of the oxides on the surface, and the reaction of these oxides with hydrogenatoms dissociated in the hydrogen environment.1. P.B. Viswathan, C.S. Swamy and V. Srinivasan, J. of the Less-Common

Metals,163 (1990) 89-108.2. M.R. Louthan, Jr., G.R. Caskey, Jr., J.A. Donovan and D.E. Rawl, Jr., Mater.

Sci. Eng. 10 (1972) 357-368.3. S. Nakahara and Y. Okinaka, Scripta Met. 19 (1985) 517-519.4. I.R. Harris, Proc. of 12th Int. Workshop on RETM Magnets and their Application,

Canberra, Australia (1992) 347-371.5. D. Moreno, E. Abramov and D. Eliezer, Scripta Met. Mat. 26 (1992) 277-282.6. D. Moreno, E. Abramov and D. Eliezer, Scripta Met. Mat. (admitted to be

published).7. D. Moreno and D. Eliezer, J. Material Science Letter (to be published).

P2.9

DECAGONAL QUASICRYSTALLINE PHASE IN THE Al - Cu - Co ALLOY

SYSTEM

B. Grushko, R. Wittmann and K. Urban

Institute fiir Festkorperforschung, Forschungszentrum Jiilich GmbH, Postfach 1913,

W-5170Jiilich, Germany

A thermodynamically stable decagonal quasicrystalline phase was first reported in Al-Cu-

Co in 1988 [ 11. In later publications it was claimed that the high-temperature decagonal

phase was sometimes replaced by complicated crystalline phases (approximants) during

cooling. The effect was interpreted by several authors as the structural instability of any

Al-Cu-Co decagonal phase at room temperature. The question of stability plays a crucial

role in the discrimination between the current theories of quasicrystals. In order to clarify

this question, a part of the phase diagram including the region of the decagonal phase was

investigated at temperatures from 550°C up to the melting of alloys [2, 3].

In the present paper a complimentary study of the decagonal phase is presented. The

study was carried out by transmission and scanning microscopy, energy dispersive X-ray

analysis. X-ray diffractometry and differential thermal analysis.

The Al-Cu-Co decagonal phase was found to behave as a stable phase in the studied

temperature range. In a wide range of alloy compositions the decagonal phase formed at

higher temperatures becomes supersaturated at lower ones as a result of the changes in the

homogeneity region. The consequences of this fact and its manifestation in the observed

electron diffractograms are discussed.

1. L.X. He, Y.K. Wu, and K.H. Kuo, J. Mater. Sci. Lett. 7, 1284 (1988).

2. B. Grushko, Phase Transitions, in press.

3. B. Grushko, Phil. Mag. Lett., in press.

P2.10

SPRAY PROCESSING OF METAL MATRIX COMPOSITES

Enrique J. Lavernia

Materials Science and Engineering, Department of Mechanical and Aeorospace Eng.,University of California, Irvine, CA 92717

Spray atomization and deposition processes provide an attractive means of combining

near-net shape manufacturing with the structural control available through rapid

solidification. This synthesis approach is currently being studied as an alternative route

for the manufacture of highly reactive (i.e., Al, Mg), high temperature (i.e., Ni, Fe),

difficult to work materials (i.e., NJ3A1), and metal matrix composites (Al/SiC,

Ni3Al/TiB2). During spray atomization and deposition, a stream of molten metal is

disintegrated into a fine dispersion of droplets using high energy inert gases. The

resultant distribution of micron sized, rapidly quenched droplets is directed towards a

substrate, where it impacts and builds up into a compact of predetermined microstructure

and geometry.

In the present lecture, the microstructures and mechanical behavior of various spray

deposited materials elucidated as a function of processing conditions, reinforcement

distribution (for MMCs), and alloy chemistry. In addition, the experimental results are

discussed and compared to those anticipated from currently available theoretical models,

paying particular attention to the synergism between processing parameters and

microstructure.

P2.11

SOME PRINCIPLES OF CREATION OF PROTECTION STRUCTURES

L.I. Slepyan

Tel Aviv University, Faculty of Eng., Dept. of Solids Mechanics Mat. and Structures,

Tel Aviv, Israel

Some principles of the improvement of the efficiency of protective structures under impact

or explosion are considered. This can be achieved by the increase of its fracture energy

(by prevention of the plastic extension deformation instability) or, in more general case,

by optimum design of material properties, for example, by reduction of its extension

resistance in the initial portion of deformation curve with its ultimate strength being held

constantly.

These structures look like a Superplastic Protective Structures (SPPS). The SPPS

possess the property to dissipate a lot of energy before it is damaged, along with the

capacity to have huge plastic strain. The process of damaging of SPPS is stable in

tension; being shocked, they deform but do not break. The SPPS are assembled out of

conventional materials, and their unusual behavior is caused by the microstructure,

namely, by special ways of elements joining or by geometrical characteristics of the

elements. Under normal conditions the SPPS behave as usual rigid materials.

Where may the SPPS be used?

(i) The SPPS are to used for construction of protective shells in which any dangerous

stuff or liquid may be kept and transported. In extreme situations or accidents the

tank made up of SPPS can be enormously stretched but remains tight.

(ii) Another use of SPPS is the protective shells for atomic power plants, chemical

plants, etc., meant to resist possible explosions and to protect environment from

pollution and/or contamination.

(iii) SPPS can be used as a material for tankers and similar bulks containing

incompressible fluids to make all the construction compressible and thus prevent its

puncture by shocks.

P2.12

IRRADIATION EFFECT ON THE PROPERTIES OF Cu-0.8% Cr ALLOY:

POSSIBILITY OF THE SLIGHTLY DOPED Cu-ALLO YS USE AS CANDIDATE

MATERIAL FOR THERMONUCLEAR REACTOR DIVERTER PLATES.

V.M. Ustinovshchikov*, L.N. Bystrov**, N.R. Bochvar**

* Advanced Technologies Center Association, Temed Industrial Park,1NFODISK TEMED Ltd., (206) Oron Rd.-Mishor Yemin Arava 86800, Israel

** A. A. Baikov Institute of Metallurgy, Academy of Science of Russia,Leninsky prospekt 49, Moscow, Russia

Electron irradiation-induced aging of Cu-0.8% Cr alloy was investigated. The

experimental conditions were electron energy about 2.3 MeV, dose-up to 2.2 x 1022 nr2 ,

experimental temperatures 15 and 100°C. It was found, that due to irradiation-induced

disintegration of supersaturated solid solution alloy electroconductivity and thus,

thermoconductivity increased. This as well as rather high mechanical properties enable us

to consider Cu-0.8% Cr alloy as candidate material for nuclear reactor diverter plates.

P2.13

h CYCLIC IRRADIATION EFFECT ON CREEP BEHAVIOR OF Fe-BASE BCC

| | ALLOYS. MODEL ALLOYS.

? L.N. Bystrov*, A.B. Tsepelev*, V.M. Ustinovshchikov**

i * A. A. Baikov Institute of Metallurgy, Academy of Science of Russia,Leninsky prospekt 49, Moscow, Russia

** Advanced Technologies Center Association, Temed Industrial Park,INFODISK TEMED Ltd., (206) Oron Rd.-Mishor Yemin Arava 86800, Israel

Experimental study of cyclic irradiation effect on creep behavior of model Fe-base B.C.C.

alloys, viz. Fe-15Cr, Fe-20Cr and Fe-4Cr-4V-4Al (wt.%), has been carried out in the

range 200-500°C. It is shown that the cycle mode irradiation leads both to the short-time

transient creep (due to dynamic dislocation bias) and the monotonous decreasing of creep

rate (because of strengthening caused by radiation-induced solid solution decomposition).

1

P2.14

f

1

REPLICATION MICROSCOPY AND A REMNANT LIFE ASSESSMENT

TECHNIQUE

B. Feldman, Y. Man and A. Kaufman

IKA, Industrial Consulting, Haifa

Throughout the world, most fossil electric power plants as well as chemical andpetroleum plants have been in operation for long periods of time-so long, in fact that theirstructural and machine components are operating beyond their original design lives of 30to 40 years. Considering the economic difficulties associated with building new plants,there is a growing need to predict life expectancy of steel, particularly those in operatingfor extended periods at high temperatures.

Several techniques can be used to obtain life-prediction information. One of them issurface replication. The area to be replicated is grinded and polished. The surface is thenetched to reveal the microstructure. A plastic film is applied, cured and carefullyremoved. The surface of the film retains a precise, reverse image of the etchedcomponent surface. In the laboratory, the replica is examined using light or scanningelectron microscopy.

There are many advantages of the replication technique. It is totally nondestructive andhence can be used for periodic monitoring. The replicas provide a permanent record ofobservations and can be stored. An accurate image of the component surface is obtained.It is capable of producing the same high-quality micrograph achieved in conventionalmetallography.

Replication is by far the most sensitive methods of examination as compared with anotherNDT methods: ultrasonic, X-ray, Dye penetrant, and magneting particle inspection. Asreplication is the direct method of detecting current creep damage of equipment, it givesvaluable information for the remaining life prediction.

The stages of damage and degradation of microstructure of pipe-lines were accuratelydetermined from the replicas. Then the remaining life corresponding to various damagestages were calculated for undamaged material, isolated cavitation, oriented cavitation,and microcracking, respectively.

For more accurate evaluation of remnant life, other methods are used, which take intoaccount the degree of microdeformation of grain (MDC method), and the number fractionof grain boundaries that are damaged by cavitation or cracking ("A" parameter).Calculations were carried out using a master curve and by the equation:

A = 0.517 (t/tr)-0.186

where:A = the number fraction of damaged grain boundaries,t = service life expected.tr = time to rupture.

The most accurate methods to evaluate remnant life combine the physical damage and thedegradation of the microstructure.

P2.15

INFLUENCE OF THE FORM OF STRESS-STRAIN DIAGRAM ON THE SHOCK

RESISTANCE OF MATERIAL AND STRUCTURES

,**f L. Slepyan* and M. Ayzenberg-Stepanenko:

.} *Tel Aviv University. Dept. of Engineering, Tel Aviv. Israel

**Negev Advanced Techn. Center. Dimona. Israel

The correlation between the material shock resistance an the form of O - £ curve (O is a

stress, and e is a strain) is investigated by computer simulation of the structure models

consisting of successively linked elements belonging to the same type with fixed tension

strength limit Of and corresponding strain limit Ef. Such models are used to describe a

plate response to the intense transverse shock. Since a structure resists mainly to tension

the membrane approach is quite relevant

The one- and two-dimensional strongly nonlinear problems of powerfool transverse

shock are analysed. The shock energy is controlled by the value and velocity of an

incident rigid mass. The geometry of the o - e curve is selected to reveal the situations

when the most of structure material is in a large strain condition.

It is found out that the shock resistance depends nonmonotonously on specific failure

energy of material. It turns out that decrease of this parameter in the initial part of the

diagram results in the rise of structure shock resistance. Conditions for obtaining the

most significant increase of shock resistance are established.

P2.16

I ENVIRONMENTAL EFFECTS ON THE BEHAVIOR OF CARBON / EPOXY

i COMPOSTTE

If Yakob Bainer*, Ariel Grinberg, E.Gutman**i,

f * Israeli Aircraft Industries, RAMTA, Beer Sheva, IsraelfI **Department of Materials Engineering, Ben Gurion University, Beer Sheva, Israel

Environmental effects of composite materials interest producers and users when structures

are designated to be used in different aggressive environments.

Environmental effects on mechanical and physical p properties of carbon/epoxy fabric

AW 30/3502 and UD AS4/3502 were tested, while exposing to water, seawater, oil and

alkaline solution (TURCO 4215-S at 60°C).

The following effects were found:

Liquid absorption in fabric is more than in UD.

The degree of environmental effect in UD composite, at length direction is more than

at the transverse direction.

. - Environment effect degree in fabric composite no difference was found between

length and transverse directions.

Wetting characteristics influence the mechanical properties, such that, when the

wetting angle is small the mechanical degradation is large & vice versa.

P2.17

ON THE STRUCTURE PERFECTION OF YTTRIUM ALUMINIUM GARNET REAL

CRYSTALS

Yuri Rosenberg and Isai Feldman

School of Physics and Astronomy, Tel Aviv University, Tel Aviv, Israel

Yttrium aluminium garnet (YAG) is one of the most widely used materials in laser

technique. In recent years the growth of these crystals doped with rare-earth elements

makes a good progress. But still the structure perfection of these crystals grown by

different methods (Czochralski, floating zone etc.) is far from desirable. Crystal growth

conditions and various defects influence on the homogeneity and optical properties of

material obtained. So the characterization of structure defects in YAG crystals is needed

and X-ray diffraction is an unsurpassed method for doing that.

The facet growth regions are the principal volume defects in YAG crystals grown by

floating zone methods. These regions are easily observed on X-ray diffraction

topographs obtained by Lang or Berg-Barrett methods. Lattice parameter study on single

crystal spectrometer by local precision Bond method shows that there is a systematic

difference between lattice parameter in faceted regions and in crystal regions free from

facets - that is true for both doped and undoped crystals.

The observed difference in lattice parameter corresponds to slightly less oxygen

octahedron rotation around < 111 > direction in facet region (3.01 degree) as compared to

facet free crystal (3.17 degree). This phenomenon is caused by distinctive atomic site

filling sequences as far as lateral growth based on two-dimensional nuc eaucvi nechanism

takes place on the facet while adhesive growth is taking place on the off-facei legion.

Integrated intensities of 16 selected X-ray Bragg anionic reflections (the structure factors

of these reflection do not contain the contribution from cations) were measured on double

crystal spectrometer. Using the intensity ratios for reflections with the same interplanar

spacing (intensities were corrected for oxygen thermal vibration anisotropy as well) we

determined anionic coordinates in YAG crystal. Combining coordinates and measured

lattice parameters we got opportunity to fix the concentration of doping elements (Nd, Lu,

Cr etc.) to within 0.03 atomic percent.

The lattice parameter increase regularities in the boundary between facet and off-facet

regions were also investigated. It was shown that rates of increase depend upon

crystallographic directions. So cubic symmetry breakdown on the facet region periphery

and corresponding birefringence take place. It is possible to describe the crystal lattice at

the facet region periphery by means of two lattice parameters: c, parallel to < 112> and a,

perpendicular to < 112> direction and c/a = 0.99995 ± 0.00001.

P2.18

EFFECT OF SHORT TIME EXPOSURE TO HIGH TEMPERATURE ON THE

TENSILE STRENGTH OF AA 2024 - T8 ALUMINIUM SHEETS

S. Bar Ziv, A. Cohen, A. Ledelsky

RAFAEL - A.D.A., P.O. Box 2250 (27), Haifa 31021, Israel

During functional operation, there are several aerospace structural components which are

exposed to elevated or high temperature. The duration of exposure is relatively short - up

to few tens of seconds. It is resulted in either by propultion motor flame or by

aerodynamic heating which is generated due to high velocity flight. The strength

properties of structural materials which are heated in this fashion may be heavily

degraded. The magnitude of degradation is controlled both by the temperature gained

material and the heating duration.

No published data were found regarding exposure times shorter then 30 min. In order to

establish the strength properties during shorter thermal exposure times (10 to 20 sec),

several tests were conducted. AA 2024-T8 sheet tensile specimens, mounted on a

servohydraulic testing machine, were rapidly heated by high intensity radiation lamps.

Tensile strength values during exposure to various temperature - time profiles, under

continous as well as pulse loading conditions, were determined. Room temperature

strength after the thermal exposure was also tested.

Strenght reduction during short time exposure was found to be substantially smaller

comparing with reduction level for 30 min. exposure. Room temperature tensile strength

was found to be dramatically influenced by the thermal exposure. Heating the specimens

to 300-420°C for only 10 sec. has resulted in yield strength reduction of about 50%.

P2.19

rTENSILE PROPERTIES OF NEUTRON IRRADIATED CO WORKED ALUMINUM

6063 ALLOY

A. Munitz*, F. Simca*, A. Stechman*, C. Cotler*. M. Talyanker**, and S. Dahan*

*Nuclear Research Center-Negev, POB 9001, Beer Sheva, Israel

**Ben Gurion University, Department of Materials Engineering, Beer Sheva, Israel

The impact of neutron irradiation of cold-worked Al-6063 on the mechanical properties

and the microstructure were investigated, utilizing optical microscopy, scanning electron

microscopy, transmission electron microscopy, and tensile measurements. No voids

could be observed up to fluences of about 3.3 x 1021 thermal neutrons/cm2 (< 0.625 eV).

The uniform elongation as well as the ultimate strength of irradiate Al increase as

functions of fluence. Metallographic examination and fractography reveal a decrease in

local reduction of final fracture necking. This reduction is accompanied with a

morphology transition from ductile transgranular shear rupture, to a combination of

transgranular shear rupture with intergranular dimpled rupture. The transgranular shear

rupture area increases with fluence. This suggests an increasing brittleness with fluence.

P2.22

MICROSTRUCTURE OF TIG AND ELECTRON BEAM COPPER-STAINLESS

STEEL WELDS

A. Munitz, C. Cotler, H. Sacham, and E, Aberman

Nuclear Research Center-Negev, POB 9001, Beer Sheva, Israel

The microstructures of TIG and electron beam copper/stainless steel weldments were

investigated using scanning electron microscopy. The relatively high cooling rates

entailing in the welding process results in high bulk supercooling, which in turn, causes

two microstructural effects:

(i) Melt separation into two liquids: copper rich (LI) and copper poor (L2). Each of the

two melts solidified according to a path dictated by the metastable phase boundary.

(ii) Enhanced solute trapping of Cu in the oc-Fe phase and Fe in the e-Cu.

P2.23

GROWTH OF A METASTABLE EIJTECTIC IN Al-U ALLOYS SOLIDIFIED IN A

COPPER MOLD

A. Munitz*, M. Talyanker**, C. Cotler*, and E. Nechama*

*Nuclear Research Center-Negev, POB 9001, Beer Sheva, Israel

**Ben Gurion University, Department of Materials Engineering, Beer Sheva, Israel

High purity aluminum (99.99%) and high purity uranium (99.9%) were used to prepare

Al-U alloys with U cc ncentration ranging between 3-22 wt.%. Alloys with the desired

composition were melted in a resistance furnace in an alumina crucible under argon

atmosphere. After allowing the melt to homogenize for several minutes, it was poured

onto a 3/4" diameter copper mold. The microstructure was examined utilizing optical

microscopy, scanning electron microscopy, and transmission electron microscopy. Two

type of eutectic microstructures were revealed. A metastable eutectic between Al and

UAI3, and a stable eutectic between Al and UAI4. The results are discussed in terms of

existing solidification theories.

y ^

P2.24

SULFUR SEGREGATION ON NICKEL SURFACES

O. Segel and M. Polak

Department of Materials Engineering, Ben Gurion University, Beer Sheva, Israel

The segregation of sulfur (bulk concentration < 200 ppm) at nickel surfaces has been

studied by Scanning Auger Electron Spectroscopy ;AES) based on the low-energy

Ni(MVV) and S(LVV) Auger transitions that are highly surface sensitive. By directing

the electron beam on selected grain surfaces, possible anisotropy in the segregation

processes could be monitored.

The main preliminary findings of the study are:

A. Diffusion coefficient and activation energies based on the time and temperature

dependencies of sulfur surface coverage.

B. Temperature independent (550-750°C) saturation coverage of half a monolayer(6 = 0.5) indicating a stable ordered structure on sulfur of the nickel surfaces.

C The Auger fine structure of sulfur [S(LVV)] changes with appearance under certain

condition, of calcium and potassium at the surface.

Future experiments aimed to elucidate effects of elastic deformation on surface

segregation are pianned.

P2.25

* POTENTIAL-CURRENT OSCILLATIONS OFTITANIUM ALLOY EXPOSED TO

| IN NaBr SOLUTION UNDER APPLIED POTENTIAL CONDITIONS

f Y. Shterenberg and D. Itzhak

K Department of Materials Engineering, Ben Gurion University of the Negev, Israel

£•'• Ti alloys of ASTM grades Ti-1, Ti-2, Ti-5, Ti-6, Ti-7, Ti-11 and Ti-12 were exposed to a

solution of IN NaBr under inductive applied DC potential conditions. With Ti-1, Ti-2,

Ti-?, Ti-11 and Ti-12 sparse but deep pits we i found. With Ti-5 and Ti-6 large number

and shallow pits were found. During the tests, harmonic oscillations of potential and

current were recorded. The phenomenon is pronounced in the monophase containing pd

alloys, Ti-7 and Ti-11, and can be also observed in Ti-1, Ti-2 and Ti-12. In double phase

alloys Ti-5 and Ti-6 the phenomenon is less apparent. Under applied potential of 5 volts

the range of potential oscillations was 180 mV in Ti-12, and 120 mV in Ti-1 and Ti-2. InTi-5 and Ti-6 the range was about 10 mV. The overall phenomenon of oscillations occursbetween the breakdown,EB , and the pitting potential, Epp, and is related to the pittingevolving processes.

P2.26

MODEL FOR PHASE FORMATION IN THIN-FILM METAL/SEMICONDUCTOR

SYSTEMS FROM AN AMORPHOUS INTERLAYER

M. Beregovsky and M. Eizenberg

Department of Materials Engineering, Technion, Israel Institute of Technology,Haifa 32000, Israel

Experimental observations of certain sequences of compound formation in

metal/semiconductor systems can not be explained by existing models. In this work we

propose a model of phase formation from an amorphous interlayer, which is formed in

many systems between the deposited metal (Me) and the semiconductor substrate (X) at

the earliest stage of reaction. The process in the Me/X system should proceed in such a

way that at any moment the degradation rate of the free energy of the system should be

maximal. The formation (or destruction) of a specific phase proceeds in accordance with

the following reaction:

Mei.Co XCo =* 1 - M e i • y x y + r M e i -c Xc

where Mei. Co XQ> is the amorphous phase formed initially between the metal and the

substrate, namely, the liquid-like solution of Me and X, Mei. y Xy is the formed

crystalline phase, and Mel - C XC is the residua! amorphous phase, which is in

equilibrium with the formed crystalline phase.

A simple analytical dependence of the free energy degradation rate for crystalline phase

formation (destruction) reactions on the composition of the amorphous interlayer and

temperature has been constructed. As a result, the sequence of phase formation in

thin-film metal/semiconductor systems can be determined. The general behaviour was

found to be bound between two limiting cases: reaction and diffusion controlled

processes. This model has been applied to the Ti/Sii_x Ge* system. It is shown that the

experimental data for Ti/Si and Ti/Ge subsystems are in good agreement with the obtained

result for the reaction and the diffusion controlled processes, respectively. Furthemore,

our model can explain in general the peculiarities of phase formulation in the complex

Ti/Si i . x Ge* system. We thank R. Ghez for useful discussions.

P2.27

ANISOTROPY DM RESIDUAL STRAINS AND LATTICE PARAMETER OF

REACTIVE SPUTTER-DEPOSITED Zr FILMS

; A. Laor, L. Zevin and J. Pelleg

| Department of Materials Engineering, Ben Gurion University, Beer Sheva, Israel

^ Lattice parameter anisotropy is a well documented phenomenon in sputter-deposited ZrN

films. The lattice parameter calculated from (111) diffraction peaks, is greater than the

lattice parameters calculated on the basis of the other peaks. The mechanisms suggested

to explain the anisotropy are discussed, and the mostly likely mechanism is indicate. The

mechanisms considered are: a) The elastic anisotropy of nitride films, b) The

rombohedral distortion, c) Selective entrapment of interstitial atoms, d) Selective growth

of lattice defects. The first two mechanisms are rejected as incopatible with the

- experimental data. The remaining two are possible but, preference is given to the

selective entrapment of interstitials. This approach is taken because it seems to explain the

development of microstrains and it is in the line with the X-ray technique applied to

evaluate macrostrains.

P2.28

I HYDROGEN INTERACTION WTTH NICKEL PRE-IMPLANTED WTTH He:| THE EFFECT OF THE DOSE AND TOOT-IMPLANTATION ANNEALING

| E. Abramov*' **, G. Solovioff**, Y. Grinberg*, G.D. Lampert*** and D. Eliezer **

| *Nuclear Research Center-Negev, POB 9001, Beer Sheva, Israel

**Department of Materials Engineering, Ben Gurion University, Beer Sheva, Israel

***Soreq Nuclear Research Center, Yavne, Israel

The thermal desorption technique has been used to study the trapping of deuterium atoms

in polycrystalline nickel pre-implanted with helium. Helium dose ranged from 1 x 1019 to

4 x 1021 ions/m2. A computer code was used to simulate the deuterium flux curves and

the trapping characteristics. The effect of post-implantation annealing at 703-923K on

trapping parameters was investigated.

The effective binding energy Ebeff, was estimated to be in the range of 0.4-0.52 eV. The

effect of helium dose and post-implantation annealing on trapping characteristics can be

related to changes in helium clusters or bubbles configuration.

The present study can improve the evaluation of hydrogen isotopes balance on future

thermonuclear fusion reactors.

P2.30

I STRESS CRACKING AS A RESULT OF HYDRIDE FORMATION IN U-0.1% Cr

S. Zalkind*. R. Ashcenazy*, S. Harush*, A. Venkert*, D. Moreno*, D. Halperin* andE. Abramov*1 **

*Nuclear Research Center-Negev, POB 9001, Beer Sheva, Israel

**Department of Materials Engineering, Ben Gurion University, Beer Sheva, Israel

The alloy U-0.1%Cr was developed for heavy water nuclear reactors. This alloy and

similar can also be used in future hybride (Fission/fusion) reactors blankets. During

service, the alloy might be exposed to hostile environments, especially, humidity, for

long periods. Corrosion and stress corrosion cracking due to humidity can cause failure

and limit the service lifetime. Therefore, it is necessary to investigate this phenomenon.

The present study reports the stress corrosion cracking in U-0.1%Cr alloy, caused by

hydride formation due to humidity.

Rivets were induced and pressed into adapted bores in plates, both made of U-0.1 %Cr.

The assembled specimens were placed for several periods of time (up to three years) in

different environments containing humidity. After aging a large amount of corrosion

products were found at the rivet-bore interface of the specimens. Radial cracks,

developed in the bore edge were detected for some specimens. X-ray diffraction patterns

of the corrosion products showed mostly UH3 and some UO2. The sample was examined

by metallographic techniques using both light and electron microscopy. The hydride

phase which was observed, penetrated int o the metal forming a needle-like shape.

Cracks were seen propagating into the hydride path.

The formation of the hydride phase, which has a much lower density compared to the

metal, yieled in a large volume change and therefore causing development of high stresses

in the interface. Calculations shows that those stresses are high enough to yield the metal.

P2.32

C VD AND MBE OF RAREFIED H2 OF SiGe SOLID SOLUTION

Klara Ljutovich

Institute of Electronics, Uzbek Academy of Sciences, Tashkent, 700143, Uzbekistan

This paper reviews our studies of SiGe such as: chemistry of growth processes, growth

kinetics, mechanisms of crystallization, parameters affected by the change in

crystallization mechanisms, etc. Particular attention is paid to the layers properties related

to the composition, thickness, surface morphology and interface character, dopants

behavior, and electrical and optical parameters.

As a result of programmed growth conditions the formation of layers with controlled Si

and Ge distribution profiles is described. Such layers are shown to have the lowest

density of interface defects and the highest mobility of carriers.

We have proposed our mode of MBE in the medium of rarefied hydrogen as an alternative

method for UHV MBE. To grow SiGe layers on Si, Ge, and sapphire substrates we

used HF-heating and autocrucible sources.

Device applications in bipolar transistors, photodetectors, solar cells etc. will also be

discussed.

P2.33

ii

THE BEHAVIOUR OF METALS UNDER INDUCED POTENTIAL

D. Itzhak* and H. Straze**

*Ben Gurion University, Department of Materials Engineering, Beer Sheva, Israel

**Bromide Compounds Ltd, Beer Sheva, Israel

Stainless steels and other passive metals like Ti, Ta and Nb (The Valve metals), are used

as construction materials in the Chemical industry. These metals, characterized by an

anodic active-passive behaviour, are generally attacked by a local type of corrosion,

usually crevice and pitting. These corrosion phenomena are accelerated under the

influence of high induced potentials. The sensitivity of AISI 316 stainless steel and the

metals Ti, Ta and Nb to induced potential terms, was investigated in electrolyte solutions,

containing bromide and chloride ions. The main results of this work are:

a: The breakdown potentials and the steady state corrosion potentials of the tested

metals are lower in chemical environments containing bromide ions with respect to

those containing chloride ions.

b: The pitting corrosion phenomena was accelerated in bromide containing solutions,

c: Crevice corrosion phenomena was accelerated in chloride containing solutions.

d: The oxide layer developed on the metals Ti, Ta and Nb was approximately ten times

thicker in solutions containing chloride ions than the layer developed on these me*als

solutions containing bromide ions.

The main finding arising from this work is the ability of the bromide ion to cause a

dielectric breakdown, in lower anodic over voltage, to isolating or semiconducting oxides

protecting the metals Ti, Ta and Nb and AISI 316 stainless steel, than chloride ion

containing media.

1

P2.36

HYDROGEN INDUCED BLISTERS FORMATION AND GROWTH IN NICKEL

PRE-IMPL ANTED WITH HELIUM

G. Solovioff*, E. Abramov** and D. Eliezer*

*Ben Gurion University, Department of Materials Engineering, Beer Sheva, Israel

**Nuclear Research Center-Negev, POB 9001, Beer Sheva, Israel

The technological interest in helium behaviour in metals stems to a large degree from

fusion first wall and fission reactor applications. In fusion reactors helium is formed in

the first wall by severe a bombardment and by tritium decay. In such a device, helium is

formed moreover, by an (n, a ) reactions whose origin is from the high flux of very

energetic neutrons (~ 14 MeV).

The purpose of this work is to analyse the effect of helium implantation and hydrogen

charging on the surface behaviour of polycrystalline nickel (99.9%).

Samples were electropolished against a nickel cathode in a 60% H2SO4 aqueous solution

at room temperature until a clean and shining surface was obtained. The electropolished

samples were irradiated with helium ions in a electromagnetic isotope separator.

Acceleration energies of the helium ions ranged from 10 to 40 keV. The samples were

cathodically charged at 10 mA/cm2 current density during 24 hr. This hydrogen charging

was carried out at room temperature in 5% H2SO4 solution, with 5 mg/l NaAsC>2 added as

a H-recombination poison. After and before every step the specimens were examined by

SEM observations and X-ray diffraction.

Whenever blisters were present after implantation, blister growth and exfoliation were

found after the later hydrogen charging. The study indicate that blisters growth can

occurs due to the coalescence of helium implantation zones. A schematic description

which explains blister formation and growth due to hydrogen charging of pre-implanted

metals will be suggested.

P2.37

I THE CORROSION BEHAVIOR OF TITANIUM-ALUMINIDE ALLOYSIi A. Ben-Gigi, G. Solovioff and D. Eliezer

I•' Ben Gurion University, Department of Materials Engineering, Beer Sheva, Israel

Modern transportation systems require minimum vehicle weight and high efficiency

power plants to achieve high performance and low full consumption. These basic criteria

apply to air, sea or ground vehicles, and in each case similar material problems limit

current design capability. Titanium Aluminides ordered aitoys: they possess high

specific strength and stiffness, excellent ueep properties, and good oxidation resistance at

elevated temperature. These properties make it potential candidate for modern

transportation systems. In view of the fact that these materials are likely to encounter

aggressive environments during service, the influence of sulphuric acid and sodium

chloride on the corrosion behavior of these materials was investigated.

The corrosion behavior was investigated by pelentiodynamic technique, and scanning

electron microscope (S.E.M) after and before being exposed to high anodic potential.

The comparison between the potentiodynamic curves and the S.E.M observations showed

a good correlation.

All specimens exhibited active to passive transition in 3% NaCl with pitting formation at

the transpassive potential. The range of passivation decreases as the amount of

aluminium in the alloy decreases.

A very stable passivation behavior was shown in all the specimens in 30% H2SO4 (except

for the Ti 25A1 lONb 3V IMo alloy). All the samples show passivation layer breakdown

and new layer rebuild.1

More corrosion aspect will be discussed.

P2.38

HYDROGEN EFFECTS IN Al-Al3Ti-SiCp

G. Solovioff*. E.J. Lavemia**, E. Abramov* and D. Eliezer*

*Ben Gurion University, Department of Materials Engineering, BeerSheva, Israel

**University of California, Irvine, CA 92717, U.S.A

Al-Ti alloys are being studied as potential candidate matrix materials in metal matrix

composites (MMCs) in an effort to further increase the alloys' modulus and strength. In

the present study, spray atomized, co-deposited and extruded Al-Al3Ti-SiCp MMCs.

Transmission Electron Microscopy (TEM) was carried out on uncharged and charged

samples in order to precisely identify the composition of the precipitates and in order to

study the hydrogen effects on the morphology.

The matrix and the precipitates were identified by a TEM-SAD pattern analysis. The Al

matrix is composed by small (0.3-1.5 |ilm) equiaxed grains that surround the elongated

A^Ti precipitates. Two classes of particles were found in the specimen: lfjrn wide and 3

to 5 \im length acicular Al3Ti particles and 3 \im irregular SiCp. The SiCp are small in

number. There are many more A^Ti particles, but both types are dispersed

homogeneously.

The results show that under severe conditions such as exposure to NaCl solutions at

cathodic charging conditions, initial crack propagation in Al-Ti/SiCp MMCs occurs

without any applied stress. In all of the samples investigated hydrogen induced crack and

voids at the reinforcement-matrix interface were present on the charged specimens.

Therefore it can be concluded that even in absence of hydride formation there is the

possibility that local increased concentrations of hydrogen exist and assist crack initiation

and growth. It would appear that for the composite, there is always the possibility for

preferential hydrogen accumulation at the large number of incoherent interfaces between

the reinforcement particles and the matrix.

P2.39

THE CORROSION BEHAVIOR OF Al / Al3Ti / SiC

N. Wertsman*, G. Solovioff*, E.J. Lavernia** and D. Eliezer*

*Ben Gurion University, Department of Materials Engineering, Beer Sheva, Israel

**University of California, Irvine, CA 92717, U.S.A

The development of advanced vehicles require several properties such as high strength to

density ratio, high creep resistance and high resistance to corrosive environments. These

requirements can be fulfilled by using Aluminium Titanium alloys as Intermetallics in

Metal Matrix Composites (MMC). Rapid solidification during the manufacturing process

will improve the performance of these materials.

This work presents a research about the corrosion behavior of the Al-3 wt %Ti

intermetallic compound reinforced by SiC particles. The measurements wee done in two

solutions, NaCl 0.5N and H2SO4 3.67N at room temperature.

The experimental methods included dipping the samples in the solutions for 24 and 72

hours and then SEM observation (surface and cross-section), WDS analysis and

quantitative X-ray analysis were carried out too. Polarization potentiodynamic curves

were used to characterise the corrosion parameters of the samples in the solutions. The

samples showed very poor resistance to the sulphuric acid environment and severe pitting

was observed, while dipping in the sodium chloride solution yielded corrosion products

which appeared as spheric salt (AICI3) particles on the surface and caused crevice

corrosion but no local pitting was found.

The polarization curves showed no passivation domain in both solutions and different

Taffel slopes in the cathodic curve.

P2.40

HYDROGEN EFFECT ON THE ORDERED ORTHORHOMBIC Ti2NbAl BASED

ALLOYS

N. Stern, G. Solovioff and D. Eliezer

Ben Gurion University, Department of Materials Engineering, Beer Sheva, Israel

The need for low density structural materials with high temperature strength and low

temperature ductility for aerospace application has driven interest in titanium aluminides,

and especially in those of the Ti-Al-Nb system.

Studies of the ternary Ti-AI-Nb alloy system have led to discovery of new ternary phases

as the ordered orthorhombic O phase. Recently discovered ordered orthorhombic (O)

Ti2NbAl-based alloys have demonstrated greater specific strength and greater fracture

toughness than current TC3 Al-Nb based alloys. The major concern in the use of this class

of materials, however, is the potential for embrittlement from exposure to hydrogen.

Because titanium hydrides are known to adversely affect the strength and ductility of

titanium based alloys, the formation of hydrides in titanium aluminides from hydrogen

absorbed during service at high temperatures upon cooling is of particular concern.

Recently, FCC of hydride phase was found in the BCC P - Ti alloy (Ti-30Mo Wt.%).

The present study was carried out on sample of Ti-22Al-2Nb at.% alloy supplied by

General Electric Alloys Properties Laboratory (USA).

The hydrogen charging was performed in a charging cell at room temperature in the

absence of any externally applied stresses in a 1 N H2SO4 solution with 0.25gr of

NaAsO2 per liter added as a hydrogen recombination poison. A platinum counter

electrode and a current density of 0.025-1 A/cm2 were used. The charging times were in

the range of 12-120 hours.

The as received specimens and the hydrogen charged specimens were characterised by

X-ray diffractometry and Scanning Electron Microscopy (SEM).

The main results for the as received specimens were:

1. The lattice parameters of the ordered orthorhombic (O) and BCC (po) phases were

determined.

2. The microstructure consists of a large amount of O phases (~nm) particles withinlarge grains of Po matrix.

The preliminary results on the potential embrittlement of hydrogen on this alloy were:

1. No significant changes in the microstructure were observed.

2. Changes of the X-ray diffraction pattern were observed as a function of the cathodic

charging times. Growth in the intensity of particular peeks may suggest a formation

of FCC-Ti 8 hydride.

F2.41

PHASE FORMATION BETWEEN CO-DEPOSITED Co-Ta THIN FILM AND SINGLE

CRYSTAL SILICON SUBSTRATE

G. Briskin, J. Pelleg and M. Talyanker

Dept. of Materials Engineering, Ben Gurion University , Beer Sheva, Israel

Metal silicides have been received much interest in recent years due to their application as

contact materials, gate electrodes, or interconnects in microelectronic devices. Binary

alloys of near-noble refractory metals have attracted interest for shallow silicide contacts

in VLSI circuits.

The object of the present work is to investigate formation in co-deposited Co-Ta film, of

1500 A thickness, on silicon n-type substrate of <100> or <111> orientation. X-ray

diffraction and transmission electron microscopy were used to study phase transitions in

the temperature range of 600-1109'C. It was found that in addition to the silicide phases

of Co and Ta, an additional intermetallic compound of Co2Ta was formed. This phase

appears only at the lower temperature range of 6OO-8OO°C. At temperatures between 900-

1100°C only the silicon rich phases were present. These are the low resistivity phases

useful in the devices. No ternary phases have been observed. It was observed that

silicide formation occurs at faster rate on <111> oriented silicon substrate.

P2.42

THE SOURCE OF FRINGE CONTRAST OBSERVED IN THE INTERFACE

BETWEEN HELIUM BUBBLE AND CuBe ALLOY MATRIX

D. Moreno* and D. Eliezer**

*NRCN, Beer Sheva, Israel

**Dept. of Materials Engineering, Ben Guiion University , Beer Sheva, Israel

The implantation of helium in metals causes the formation of helium bubbles and creates

an order array called bubble superlattice. This phenomenon has been investigated widely

and the most extensive studies of the structural nature of the gas bubbles super-lattice

have been for copper [1-3]. At low implantation temperatures, vacancies have only

limited mobility. In this case, the bubbles are overpressurrized and grow by an athermal

process such as dislocation punching. The lattices of the arranged bubbles and the matrix

of the host metal are oriented for diffraction along common planes but there is little

understanding of the helium structure inside the bubbles. In theoretical studies, the

calculated helium pressure arrives at values that are consistent with solid state helium. As

a result of the typical size of these implanted bubbles, there is no technique available to

prove this statement.

The present work reports on the observed contrast features at interphase interfaces by

high resolution transmission electron microscopy. The principal features are interfacial

dislocations by means of Aw fringes [4]. Aco fringes generally arise at interfaces having

correlated lattices which ar oriented for diffraction by common planes such that the

deviation parameter a> is different for each crystal structure. The finite value of Ao) arises

from a misfit between the host metal lattice around the bubbles and the helium structure.

This misfit increases by the strain field created in the interface as a result of the bubbles

growth and displacement of the bubble interface. The observed Aco fringes around the

bubbles raise the possibility that the helium atoms are arranged in a specific structure since

the Aco fringes are usually obtained by interaction of two lattices at the interface.

REFERENCES

1. P.B. Johnson, A.L. Malcolm and D.J. Mazey, Nature 32, (1987), 316.

2. P.B. Johnson, A.L. Malcolm and D.J. Mazey, J. Nucl. Mater. 152, (1988), 69.

3. P.B. Johnson, A.L. Disprose (nee Malcolm) and D.J. Mazey, J. Nucl. Mater. 158,

(1988), 108

4. R.C. Pond, J. of Microscopy 135, (1984), 213-240.

P2.43

FCGR AND FRACTURE TOUGHNESS IN Ti-6AI-4V OF DIFFERENT

MORPHOLOGIES

J. Brandelstein* and L. Levin**

*Metal Technologies Center, RAFAEL, Haifa, Israel

••Department of Materials Engineering, Technion, Haifa, Israel

Modifications to the microstructure of Ti-6A1-4V were obtained, from a series of

thermomechanical, thermochemical and two-stage thermal treatments which included

temporary alloying with hydrogen.

Values of fracture toughness Kjc and rates of fatigue-crack growth (FCGR), da/dN vs

AK, were determined for each microstructure.

The influence of the phase and morphological structure of the material on each region on

the da/dN curve was examined, and a considerable dependence on the morphology was

found for the I and HI regions.

It was shown that the transition point between the I and II regions can be calculated from

morphological data which was obtained by means of an image analyzer.

The results indicate optimal values of fracture toughness in microstructure of the Broken-

up type.

P2.44

THE EFFECT OF MACHINING PARAMETERS ON THE SURFACE ROUGHNESS

OF Ni COATED Al MIRRORS

G. Kohn*, Y. Shneor** and R. Papiar***

*Dept. of Materials Engineering, Ben-Gurion University, Beer-Sheva, Israel

**Rotem Industries Ltd., Rotmax Division, Beer-Sheva, Israel

***Israel Aviation Industries, Yahud, Israel

The Rotmax Division of Rotem Industries Ltd., has been engaged for some time, together

with the scientists of the NRCN, in the development and manufacture of components

which demand ultra-precision engineering. The final machining steps of these

components are done by computer-controlled ultra-precision diamond turning lathes

(PDT).

PDT systems are used in the manufacture process of optical components with stringent

requirements on surface quality and dimensions. Flat, spherical and aspherical metal

mirrors for laser applications, video tape recorder heads, and memory discs for

computers, are a partial list of components manufactured using this method. The metals

which are commonly used as substrate materials are among others, aluminium, copper

and molybdenum. The surface quality achieved by PDT is a few hundredth of a

micrometer with dimensional tolerances of several micrometers.

Natural diamond cutting tools, with a very sharp cutting edge, are used in this machining

process. Linear cutting speeds range between 100-1000 mm/min and the depth of cut

very from 1-50 \xm. Tool motion per revolution is dependent on tool radius and the

desired surface quality, and ranges between 0.5 and 10 |im/rev.

This paper describes the general features of the ultra-precision diamond turning facility

available at Rotmax Division. The production steps of nickel-coated aluminum mirrors

are described together with the necessary testing procedures involved in the evaluation of

the final surface roughness of the product

P2.45

A NEW SELECTIVELY ABSORBING COATING

T. Werber and J. Yahalom

Department of Materials Engineering, Technion-Israel Institute of Technology, Haifa,32000, Israel

A novel kind of selectively absorbing coating for operations at temperatures higher than

300°C has been elaborated. The selective absorbing surface is an absorbing reflecting

tandem NiO/Ni2Al3. The preparation of the selective absorbing surface is based on the

formation of a nickel aluminide coating following conversion of its upper layer into an

NiO layer by a chemical conversion process. Optical tests (hemispheric reflectance,

absorptivity and emissivity measurements) have shown that the coating's selective

absorbing properties are very good. In addition, the coating has high stability against

environmental deterioration.

P2.45

CONTROLLED THERMOPROTECTTVE COATING? FOR GAS TURBINES

E. Shvarzshtein, T. Werber, J. Yahalom

Department of Materials Engineering, Technion-Israel Institute of Technology, Haifa,32000, Israel

It is imjpossible to prevent ash deposition in the hot gases duct when the concentration of

solid impurities in the gas stream exceeds the order of 1 ppm. The proposed approach

consists of utilizing oxide-based deposit formations for increasing the surface durability

of turbine blades and vanes. A basic factor in the protecting action of this kind of deposit

is mass exchange with the working environment. The deposits are converted into a

dynamically sustained coating when they survive as entrainment or wear loss. These

deposits are built up by the environment throughout the operation period. This kind of a

coating is termed a controllable thermoprotective coating (CTC).

A CTC acts as a protective layer against material losses caused by wear of hot combustion

gas streams, as well as erosion by impact of solid particles in such streams. The CTC

also acts as thermoprotective barrier coating (TBC) because the deposit has a low thermal

conductivity. The anticorrosion protection of CTC has an indirect character. The

oxidation rate of the superalloy support is diminished in consequence of a decrease in the

component temperature in TBC action as well as by suppressing the erosion in the

synergetic oxidation-erosion process.67

P2.47

THEORETICAL METHOD FOR CALCULATION OFTHE DIFFUSION DEPTH

C. Samoila

University Transylvania of Brasov

The paper presents a theoretical method based on the dimensional analysis through which

can be established an analytical correlation of the factors that characterise the phenomena

of diffusion at thermochemistry treatment; when the number of these factors surpass the

possibilities of Fick's law.

The examples will refer to the sulphatization of the small pieces of alloys.

P2.48

METHODS FOR OBTAINING METALLIC MAGNESIUM FOR MODIFICATION OF

NODULAR CAST IRON

A. Crisan and I. Ciobanu

University Transylvania of Brasov

The paper presents a study about the production of granular metallic magnesium, a study

that can be used at modification of S.G. Iron.

Through general methods used for obtaining metallic granules, the paper presents two

methods - the centrifugal casting and the vibratory stress of liquid alloy. After delivery or

some conclusions about theoretical methods there are presented some equipment for

laboratory and the experimental results. It makes a comparison between the theoretical

and experimental results for the laboratory equipments that are used.

The conclusions about the ways for obtaining granular metallic magnesium with good

quality for modification of S.G. Iron are presented.

P2.49

HYDRIDES FORMATION IN ct2 AND yTITANRJM

M. Dangur, J. Haddad and D. Eliezer

Dept. of Materials Engineering, Ben Gurion University of the Negev, Beer Sheva, Israel

I lydrogen degradation of the mechanical and fracture behavior of titanium alloys can be a

complex process, influenced both by hydrogen transport and the form and extent of the

hydrogen-material interactions.

A preliminary study was conducted on hydrogen embrittlement of titanium alloy. The

main results of the present study show that hydrogen induced cracking or hydrides

formation in ct2 and y.

There is a general agreement as to the segre^'ion of hydrogen from the metal matrix to

preferred location. The trapping of hydrogen is caused by the existence of locations

which have an energetic locations in the lattice. The theoretical approach to hydrogen

brittlements of intermetallic titanium 012, and y is concerned with the development of

mechanisms which explain the kinetics of the trapping. The dislocations cause mobility

which leads to convergence. At this point, nucleation and growth of new brittle hydride

phase take place.

P2.50

Ge SIGLE CRYSTAL FILMS GROWN BY MBE ON (Ca, Sr) F2 / AL2O3 AND GaAs

SUBSTRATES

E. Redmard*, E. Griinbaum* and G. Deutsher**

*Faculty of Engineering, Tel Aviv University, Ramat Aviv, Israel

**School of Physics and Astronomy, Tel Aviv University, Ramat Aviv, Israel

Ge single crystal (S.C.) film is an attractive choice both as a bottom cell and as substrate

for CaAs and AlGaAs top cell growth in tanden solar cell configurations.

High purity S.C. Ge films were grown in UHV system by MBE (Molecular beam

epitaxy) on GaAs (100) S.C. wafers and on Cao.4Sro.6F2 S.C. films grown in turn on

AI2O3 (1T02) substrates.

Large area ( 2 x 2 cm2), 3 - 1 0 |Am thick, self supporting Ge films were obtained by

etching away the (CP, Sr) F2 inter layer thus separating the Ge film from the sapphire

substrate. The sapphire substrates were reused after proper cleaning. The films were

studied by SEM, RHEED and XRD.

P2.51

WIDE ANGLE XRD STUDY OF THE EFFECT OF PROCESSING CONDITIONS ON

POLY (P • PHENYLENE 3ENZOBKTHIAZOLE)

E.L. Garstein and Y. Cohen

Department of Chemical Engineering, Technion, Haifa 32000, Israel

Fibers and films exhibiting exceptional mechanical properties have been developed from

rigid rod polymers by processing from solution in a way which provides very high

alignment of the rigid chains. The success in translating the molecular strength and the

stiffness of the individual rigid chains to macroscopic properites relies on suitable

morphology on the supramolecular scale, and it is therefore important to characterize the

microstructure on this scale.

In continuation of our SAXS study1 of polymer wet films as-dried in a supercritical CO2

and also subjected to heat treatment by drawing trough the furnace at 600°C for 10 sec,

we have performed meridional scans (in the direction of fiber axis) employing

symmetrical transmission technique and equatorial scans (perpendicular to the fiber axis)

employing symmetrical reflection technique. The presence of the multiple meridional

reflections pointed to a good orentation of the molecules, as well as to the high degree of

axial order. From the WAXS photographs recorded using Statton camera, the preferred

orientation was found to improve according to the azimuthal angle a = 27° - 30° to

a = 22° - 25° for the as-CC>2 dried and the heat treated films, respectively. The

equatorial scans showed that the 3-D crystallinity improved with heat treatment, since the

overlapping reflections became better resolved. The lateral size of the crystallites

estimated from the breadth of the equatorial peaks using the Debye-Scherrer formula

increased from 4 nm to 11 nm. The observed sharpening of the meridional reflections

with heat treatment also indicated on the possible combination of the reduction of the

disorder and/or increase in the crystallite size.

It is much of interest now to apply the paracrystallinity models for the detailed

interpretation, of the diffraction spectra.

1. Y. Cohen and E. Garstein, Proc. 5th Isr. Mater. Sci. Soc., Haifa (1990), p. 259,

eds. M. Bumberger and M. Schorr, Freund Publishing House, Ltd.

P2.52

OXIDATION GROWTH EM INTERMETALLIC Ti-25-10-3-1

M. Dangur and D. Eliezer

Dept. of Materials Engineering, Ben Gurion University of the Negev, Beer Sheva, Israel

Reactive elements that contain intermetallic OC2 + P titanium quickly develop oxide by ionic

reaction to receive type of oxides such as: T1O2, AI2O3 and NbO2- The oxidation kinetics

and morphological features of the intermetallic Ti-25-10-3-1 were investigated. The

comparison with the oxidation kinetics of T13AI + P is given by weight gain-oxidation

time curves. In the early stage of oxidation, the curves show a parabolic shape indicating

formation of a protective oxide thin scale, probably A2IO3, which avoids formation of

another brittle oxides in this stage. After the initial transient period, the curve become

linear. This behavior of the curve is due to high diffusivity of titanium in AI2O3 scale,

resulting in the formation of T1O2 crystalline phase as an external scale. The nucleation

and growth of TiO2 phase in the AI2O3 scale produces many pores in particular at the thin

scale AI2O3 from 15 fxm to 150 Jim T1O2 oxidation layer. Sufficient aluminium transport

from Ti-25-10-3-1 assists the formation of the AI2O3 scale, but it cannot act as a protective

film against oxidation. High aluminium concentration in various type of intermetallic

titanium can be protective against oxidation and can be used as a coating material.

P2.53

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